All seasons arena sets bonuses merged
A very interesting change, you can wear parts of the gladiator sets and get the bonuses even if they're from different seasons. Obviously this also means that you won't be able to stack two +35 Resilience bonuses anymore. Old sets bonuses will be changed to new ones.

Quote from Blizzard staff
General
 
    * (4) Escape Artist has now a 1:45 minutes cooldown.
    * (4) All Disarm immunity effects in the game were changed to 50% disarm duration reduction (non stacking).
    * (3) Auction's duration have been changed to 12, 24 or 48 hours. Also deposit prices for all duration will be the same.
    * (3) You can now ctrl+click recipes to get a preview of the crafted item in the dressing room.
    * (3) All items of the auction house will be sorted server side, basically it means that when you'll try to sort a particular item by price, it will sort it through all page, not only the current one.
    * Healing Reduction effects now affect all Drain spells and abilities (i.e. Mortal Strike will affect Drain Life) (Source)
    * Level 20-60 Quest EXP has been increased, while EXP to Level has been decreased (Source)
    * Guild Banks are being added to the game. (Source)
    * New relics are added to support all talent trees in patch 2.3 for Shaman, Paladins and Druids. Most of the arena-system existing Relics have been renamed to create a more consistent naming convention (Source)
    * +Healing bonus will give 33% of spell damage as well (1500 Healing bonus will give you 500 Spell damage) (Source)
 
Raids & Dungeons
 
    * (3) New daily quests are available in the Lower City for 5 man heroic and non-heroic dungeons (Once at a time, a bit like battlegroundw weekends, each day you will get quests for a different dungeons). The following non-heroic dungeons are concerned : Shattered Halls, Steamvault, Shadow Labyrinth, Black Morass, Botanica, Mechanar, and Arcatraz. All dungeons will get quests in Heroic mode. If you're getting the non-heroic and the heroic quest on the same day for the same dungeon, you can complete both by running it in heroic mode once. Non heroic quests will reward you with a Ethereum Prison Key (various reputation), gold, and reputation with the Consortium. Heroic quests will give you 2 Badges of Justice, gold, and reputation with the Consortium.
    * (2) Mobs inside Sethekk Halls will now continue to award Lower City reputation all the way into Exalted. Previously they stopped giving reputation in non-heroic mode just before players hit revered.
    * (2) The number of creatures that must be killed in the Karazhan Servants Quarters area before a miniboss spawns has been reduced.
    * New Title - Champion of the Naaru: Awarded to those who complete the Tempest Keep attunement quest at level 70. (Won't be available anymore at lvl 80) (Source)
    * Heroic Badges drop from Zul'aman and Karazhan bosses.
    * The amount of items available from the Heroic Badges vendor has been considerably increased.
    * New 10-Man Raid - Zul'Aman!
 
 
Zul'aman
 
    * Zul'Aman will be a 10-person raid zone
    * Zul'Aman will be on a quicker reset than 7 days (some might call this "casual" )
    * Zul'Aman will be MORE difficult than Karazhan and drop better loot (some might call this hardcore)
    * Zul'Aman will feature 6 bosses and it's our goal that you can kill them all in one night -- perhaps 2-3 hour clear times (some might call this casual)
    * Zul'Aman will not have a key requirement. Nor will it have an attunement quest\ (some might call this casual)
    * Zul'Aman will have a VERY challenging timed quest for those who choose to participate in it. This *will be* hardcore and will be very rewarding. Players do not have to engage in the timed run (very similar to the Baron run in Stratholme)
    * We're tuning the first boss in Zul'Aman to require less raid coordination than some other raid bosses. He will still hit very hard so you'll need to be geared properly but it won't take 15 minutes to explain the fight. It will be a simple yet challenging fight. The other boss fights get more complex and challenging from there. If players want a basis of comparison, imagine the tuning of ZA started around Nightbane/Prince difficulty and ramped up from there.
 
 
Factions
 
    * (3) You can buy now buy Super Mana and Health Potions from Ogri'la quartermaster. They're usable everywhere and costs 50 Apexis Shard.
    * (3) New Flying Mount added. Requires 2,000g and Exalted with Cenarion Expedition. (280% Speed) (Source)
 
PvP
 
    * (4) New healing wand for Season 3 Arena.
    * (4) New Melee PvP Cloak added to the game: 34 Stamina, 20 Crit, 20 Resilience, 46 Attack Power, 112 Armor Penetration.
    * (4) New Caster PvP Cloak added to the game: 34 Stamina, 15 Intellect, 16 Spell Crit, 23 Resilience, +27 Spell Damage/Heal.
    * (4) New Healer PvP Cloak added to the game: 34 Stamina, 15 Intellect, 6 mana/5sec, 23 resilience, +51 healing (+17 spell dmg).
    * (4) Vengeful Gladiator's Waraxe added to the game: 62 Stamina, 46 Crit, 33 Resilience, 15 Hit rating, 92 Attack Power, 98 Armor Penetration. Waraxe Cost: 1000 arena points (no rating requirement).
    * (3) New battleground rewards are available : boots, belts, and bracers. (Source)
    * (1) New daily quests for battlegrounds have been added, they're dedicated to one specific battleground each day, are available to players of all levels, and reward experience, gold, and honor (Source)
    * (2) Spells now cast for free before a Battleground begins
    * (2) Spells now cast for free for 5 seconds after resurrecting at a Spirit Healer in Battlegrounds
    * (2) Additional Honor is rewarded upon conclusion of Warsong Gulch, Arathi Basin, and Eye of the Storm
 
Arena Season 3
 
    * (4) You will need 1850 Team and Personal rating to buy weapons.
    * (4) You will need 2000 Team and Personal rating to buy shoulders.
    * (4) All items in the gladiator season 1, 2, and 3 sets will be part of the same set, so you can use those items interchangably and keep the set bonuses
    * (4) Many of the Arena Sets bonuses have been updated.
    * Season 1 arena gear will be available from honor points vendor when the season 3 starts.
 
 
Mages
 
    * (2) Detect Magic removed. All players may now see their target's beneficial effects at all times
    * (2) Frost Ward and Fire Ward now gain additional benefit from +Dmg
    * (2) Frost Ward and Fire Ward (Ranks 5, 6) have had their base absorb lowered
    * Damage coefficient reduction is removed from Improved Fireball/Frostbolt. (Source)
    * New spell : Ritual of Refreshment. It will allow players to pick up their own stack of food/water, similar to a Soulwell. (Source)
    * Evocation restores 15% of your total mana every 2 seconds instead of being a spirit-based mana regen increase. (Source)
    * Arcane Meditation is being increased to 10/20/30% mana regeneration. (Source)
    * Ice Barrier gains additional benefit from spell damage bonuses. However, the base absorb values of ranks 5 and 6 have been reduced. (Source)
 
Shamans
 
    * (2) Item - Tidefury Raiment now grants additional mana to Water Shield
    * (2) Item - Totem of the Thunderhead now grants additional mana to Water Shield
    * (2) New Talent - Shamanistic Focus: After landing a melee critical strike, you enter a focused state. The focused state reduces the mana cost of your next Shock spell by 60%
    * New Talent replacing the 2 Handed weapons one - Elemental Focus: Puts you in a "focused state" after landing a melee critical strike, reducing the mana cost of your next Shock spell by 60% (Source)
    * All shaman can equip 2-Handed Axes and 2-Handed Maces without spending talent points. (Source)
    * Frost shock is no longer subject to diminishing returns. (Source)
    * Shamanistic rage also reduces all damages taken by 30% for the duration of the ability (30 seconds) in addition to its current effect. (Source)
    * Spirit weapons reduces melee threat by 30% instead of 15%. (Source)
    * Mental Quickness adds 10/20/30% to spell damage and healing bonuses based on your total Attack Power in addition to it's current effects. (Source)
    * Lightning Overload now has a 4/8/12/16/20% chance to proc (Source)
    * Lightning Overload damage has been decreased by 50% (Source)
    * Lightning Overload now causes 0 threat (Source)
    * Lightning Mastery reduced to .1/.2/.3/.4/.5 seconds (Source)
    * Mana Spring Totem now restores mana at a rate of 20 mana every 2 seconds (Source)
    * Water Shield now costs 0 mana to cast, and the mana per globe has been substantially increased (Source)
    * Water Shield's duration has been reduced to 1 minute, and grants mana for each globe left upon ending (Source)
    * Elemental Focus will now reduce the mana cost of your next two damage spells by 40% (Source)
    * Lightning Bolt casting time reduced to 2.5 seconds, and mana cost decreased (Source)
    * Chain Lightning casting time reduced to 2 seconds, and mana cost decreased (Source)
 
Druids
 
    * (1) Many new macro inputs as well as druid 'cancelform' becoming an instant like 'dismount'. (Source)
    * Cure Poison and Abolish Poison may now be cast in Tree of Life form (Source)
    * Remove Curse may now be cast in Moonkin form (Source)
    * Rebirth cooldown reduced to 20 minutes (Source)
    * Intensity increased to 10/20/30% mana regeneration. (Source)
 
Warlocks
 
    * (2) Banish may no longer be cast on targets tapped by other players
    * Ritual of Souls has had it's casting time significantly reduced. (Source)
    * Healing Reduction effects now affect all Drain spells and abilities (i.e. Mortal Strike will affect Drain Life) (Source)
 
Warriors
 
    * (1) Weapon Mastery has been changed to reduce the duration of Disarm effects by 25/50% (Source)
    * Mace Specialization proc has been reduced (Source)
    * Mace Specialization Rage increased to 7 instead of 6 (Source)
    * Tactical Mastery now greatly increases threat from Mortal Strike and Bloodthirst while in Defensive Stance (Source)
    * Devastate now combines the effects of Sunder Armor into it's effect, and is affected by all talents and items that affect Sunder Armor (Source)
 
Priests
 
    * (4) Elune's Grace (Night Elf Priest Racial)effect changed to reduce chance to be hit by melee and ranged attacksby 20% for 15 seconds. There is now only 1 rank of the spell.
    * (4) Power Word: Fortitude, Divine Spirit, Prayer of Fortitude and Prayer of Spirit will have their mana costs reduced.
    * (1) New Dwarf/Draenei ability - Chastise: Causes Holy damage and incapacitates target for 2 seconds (Source)
    * (1) Fear Ward will now be available to all Priests at level 20 (Source)
    * (1) Fear Ward duration reduced to 3 minutes, and cooldown increased to 3 minutes (Source)
    * Power Word: Shield gains additional benefit from spell damage and healing bonuses. However the base absorb values for ranks 10, 11, and 12 have been reduced. (Source)
    * Pain Suppression is castable on a friendly target, it reduces the target's threat by 5% and reduce the damage it takes by 40%. (Source)
    * Pain Suppression cooldown is reduced to 2 minutes. (Source)
    * Meditation is increased to 10%/20%/30% Mana regeneration. (Source)
    * Prayer of Healing, Circle of Healing and Holy Nova (healing effect) gain additional benefit from damage and healing bonuses. (Source)
    * Circle of Healing base amount of healing is reduced, but it gets more bonus from +healing effects. If you have more than +1338 healing you will see it heal for more. (Source)
 
Paladins
 
    * (2) Vindication (Retribution) frequency and duration increased and now reduces all attributes by 5/10/15%, not just Strength and Agility.
    * (2) Pursuit of Justice (Retribution) is now 3 ranks and increases movement speed by 5/10/15% and also reduces the chance you'll be hit by spells by 1/2/3%.
    * Exorcism's mana cost has been lowered (Source)
    * Holy Wrath's mana cost has been lowered (Source)
    * Hammer of Wrath's mana cost has been lowered (Source)
    * Vengeance has been increased to 30 seconds (Source)
    * Improved Seal of the Crusader effect added to base abilitiy (Source)
    * Improved Seal of the Crusader now gives the effects of Sanctified Crusader (Source)
    * New Talent - Sanctified Seals (replacing Sanctified Crusader): Increases your chance to critically hit with all spells and melee by 1/2/3%, and reduces the chance your Seals can be dispelled by 33/66/100% (Source)
    * Crusader Strike cooldown is being lowered to 6 seconds. (Source)
 
Rogues
 
    * (2) Poisons now enchant weapons for 1 hour
    * Fleet Footed increased to 15% speed increase
    * Deadly Throw traveling speed is being increased significantly, it will reach your target faster and the snare will last one second longer. (Source)
    * Ruthlessness won't be triggered by Deadly Throw anymore, and Ruthlessness will be changed to only affect melee finishing moves as a whole. (Source)
    * Blind no longer requires a reagent, is changed to a physical attack, will share the same diminish category as cyclone, and will diminish in PvE as well as PvP. (Source)
    * Shadowstep can be used at any time (even when you're not stealthed). After the use of Shadowstep threat caused by the next Ambush, Garrote, or Backstab will be reduced by 50%. The cooldown will be increased to 40 seconds. (Source)
    * Dirty Deeds increases the damage of special attacks by 10%/20% against targets that are below 35% health in addition to its current effect. (Source)
 
Hunters
 
    * (2) Trueshot Aura (Marksmanship) no longer costs mana to cast and will last until cancelled.
    * (2) Serpent Sting, Immolation Trap and Explosive Trap now all gain additional damage based on 10% of your ranged attack power.
    * (2) Wyvern Sting (Survival) is now instant cast and has a maximum duration of 10 seconds in PvP.
    * (1) 20 and 24 Slots ammo pouches have been added (Source)
    * Arcane Shot (Rank 6+) will now dispel 1 Magic effect in addition to damage (Source)
 
Engineering
 
    * (4) Flying Mount added for Engineers. Regular and Epic version. It will not require any Nether Vortex. (Source)
    * (4) New Field Repair Bot will repair, buy, sell, like a normal repair bot, but it will also sell all reagents, level 65 arrows and bullets, poison reagents, few types of vials, up to 2 super mana/healing potions, and maybe some scrolls. These are all for sale, with no rep discount, because he’s a robot. (Source)
    * New Plans - Field Repair Bot: Dropped by Gan'arg Analyzers in Blade's Edge Mountains. (Source)
 
 
Enchanting
 
    * (2) Duration of Wizard and Mana oils has been increased
 
Fishing
 
    * Fish nodes Tracking may be learned from a journal fished from crates (Source)
    * New fish added near Karazhan and Zul'Aman (Source)
 
Cooking
 
    * New Daily Quests (Source)
    * New recipes added for fish found near Karazhan and Zul'Aman. (Source)
 
Interface
 
    * (1) Mailboxes are upgraded to handle up to 12 items per mail. (Source)
    * (1) Auction House scanning will receive its own API letting you scan the whole AH every 15 minutes with any addon. (Source)
    * (1) Many new macro inputs as well as druid 'cancelform' becoming an instant like 'dismount'. (Source)

* (4) Power Word: Fortitude, Divine Spirit, Prayer of Fortitude and Prayer of Spirit will have their mana costs reduced.
    * Meditation is increased to 10%/20%/30% Mana regeneration. (Source)