The following is a list of undocumented changes observed by players. They may not be agreed upon by everyone. They are not part of the official Blizzard release notes.
Druid
Not all characters received a talent reset.
When stealthed, there is now an indicator above the heads of mobs that can see through stealth.
When in Aquatic Form, the view has changed to an above-the-water angle, instead of the previous below-the-water angle.
Barkskin now has a 2 minute cooldown.
Tree of Life changes: now has the a dancing and eating animation; backward movement animation fixed; no longer makes a bear roar when shifting into a tree; changes to casting animations.
Bears make kitty sounds when performing Mangle.
Hunter
Flare has a longer time before it actually appears on the ground, but brings targets out of stealth just the same.
Steam Tonk Controllers now work properly for hunters.
Feign Death reaction time slowed down. Doesn't kick in until animation stops.
Snake Ability "Poison Spit" tweaked. Less damage, over less time, and with a longer cooldown.
Mousing over your own stats now tells how much your pet's stats are improved.
The Pet Info tab now provides the same detailed information as the character tab. Side note: Warlock pet spells now scale with gear and talents (instead of only melee attack power). Does this apply to Hunters too?
The hunter pet ability "Gore" is now in game and can be learned from boars.
All pet attack speeds have been normalized to 2.0.
Hunter's Mark no longer has a casting animation.
Feign Death no longer shakes off pets. (bug?)
Hunter no longer grows in size when under the effect of The Beast Within, he/she just turns red.
Mage
[Netherwind Mantle] graphics have been returned to normal and have a higher particle rate than before the original change.
Polymorph resist rate increased. (?)
Arcane missiles does 25% less damage costing 15% less mana.
Paladin
Crusader Strike cooldown increased to 10 seconds, from 6 seconds.
Vengeance talent is now 10% for 5 points, from 15%.
Mana cost reduced for Judgement, Cleanse and Redemption.
Coefficients upped for Consecrate and Avenger's Shield.
Priest
Holy Fire's graphic is now back to the original.
Holy Specialization is now correctly displayed in the spell section of the character frame.
Inner Focus now gets used up when casting Divine Spirit or Prayer of Spirit.
Rogue
Not all characters received a talent reset.
Venomous Totem changed/nerfed.
Improved Backstab switches places with Improved Slice and Dice in the Combat tree.
Improved Sap switched places with Elusiveness in the Subtelty tree.
Improved Sap now costs 2 points for a 100% chance to return to stealth.
Auto-Loot now works with Pickpocket.
Blinding Powder has a new icon.
When stealthed, there is now an indicator above the heads of mobs that can see through stealth.
Every rogue has their own Deadly Poison debuff slot on monsters, instead of 1 for all.
Shaman
You can now speak to NPC's in Ghost Wolf form.
Rockbiter ability now adds set amount of dps (rank 4 is +9 dps). It also no longer procs on every hit.
Casting shaman weapon buffs no longer have an animation.
Totemic Call added, to pick up totems.
Warlock
Demon Armor spell cost reduced 45%.
10% damage recuction on Corruption and Curse of Agony.
50% damage reduction on Curse of Doom.
Curse of Doom proc (summoned Doomguard) no longer despawns the current Warlock pet.
Mousing over yoru own stats now tells you how much your pet's stats are improved.
The Pet Info tab now provides the same detailed information that the character tab does.
Warlock pet spells now scale with gear and talents (instead of only melee attack power).
Steam Tonk controllers now work properly for Warlocks.
Warrior
The graphical effect on a mob when Devastate is used has been greatly increased in size.
Items
Epic (all?) shields have had their armor and block values increased by 15%.
Enchantments on items have now been returned to their original green color (they were white for a while).
Thunderfury's proc now sounds like Thunderclap.
Steam Tonk Controllers got a new icon and now work properly for Hunters and Warlocks.
Kodos have their 'spacebar animation' back, where they look side to side and grunt/roar.
[Helm of Valor] now displays facial hair when worn. Causes some clipping issues. (bug?)
The Zergling's chomping sound that was introduced in the previous patch was taken out.
Tonk Controller icon changed to look like a remote control.
[Tabard of Frost] and [Tabard of Flame] are now epic.
PvP
High Warlord's Offhands cost reduced to 20 Marks of Honor (down from 40).
Level 70 rings doubled in honor cost.
Mage HWL/GM Robes cost reduced to 30 AB marks (down from 60).
Tauren can now ride the Black War Raptor.
They put the 1-minute 'gong' reminder back into battleground queues.
In the Battleground Stat screen, ranks are no longer displayed. Instead, icons representing the class of the character are now shown.
Unused Battleground tokens can now be used to purchase Level 61 healing and mana potions. 2 marks per potion.
The Horde vendor is ini the Hall of Legends. Not sure about Alliance.
Estimated Honor is now showing up correctly.
Tradeskills
[Design: Citrine Pendant of Golden Healing] is now BoP.
Unsmelted mineral ores (Copper, Iron, Thorium, etc) now stack up to 20, increased from 10.
New level 1 cooking recipe [Spice Bread] available at cooking trainers.
New cooking recipe [Simple Flour] sold at cooking vendors.
Charred Wolf Meat has had its trivial level increased (still green at 84).
Many enchantments that were previously dropped can now be trained at the Master Enchanter in Uldaman .
New Armorsmith recipes added (Earthroot Leggings, Windforged Leggings).
New Dragonscale Leatherworking leg pattern added to Dragonscale trainer.
Quests
Quest Items can now be removed fro your bank upon completion of the quest. (no longer to be in your character's backpacks)
Wildhammer repeatable turn in quest removed.
The drop rate of arcane crystals was boosted. (?)
Thorium Shells are now green at 300 Engineering. (was orange at 300 before this patch)
Interface
'Elite' quests renamed to 'Group' quests.
Initiationg Auto-Attack on a target shows an animation where the targeting circle gets bigger and then shrinks.
Before the patch, if you locked your toolbars, you could still move icons around using Shift + Left-Click. Now you have to drag instead of click.
Misc
Riding Skill (150) cost reduced from 800g to 600g.
There is no longer a Shoot Crossbow, Shoot Gun, or Shoot Bow. They have all been replaced with Shoot.
Ishar's J-Boots are slower. The ancient cyclops laughs approvingly.
WoW no longer works at all on laptops with Intel 915gm video chipsets.
Hippogryphs and Gryphons now make noises when flying.
Wildhammer faction removed.
Spirit Healers now appear on Minimap while dead.
All abilities that cost a % of base mana have had their mana cost reduced.
Gadgetzan now has snipers on the roofs to stop people from rooftop camping.
Sylvanas now has a normal dialogue even when she isn't offering a quest. Before, she had no dialogue when you clicked on her.
Hemet Nesingwary moved from Stranglethorn Vale to Nagrand . In his place is now his sone, Hemet Nesingwary Jr.