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.
Environmental sounds play in the background on the Character Creation screen.
Some newly-created characters start out with their racials on their action bar. (I.E. Night Elves start with shadowmeld, humans don't start with perception on their bars)
Moonfire now has a moon in the animation.
New Loading screens.
Escape artist is now instant cast.
Blood Fury also increases spell damage depending on your class. Increases Ranged and Melee damage for Hunters (unconfirmed).
The Troll Priest racial "Shadowguard" now has a different graphic for the floaty orbs.
The Looking For Group channel has been removed.
Same-faction players in stealth are seeable by any other player of that faction.
Phase Shift has a new sound effect.
Added a new Sound Levels option under sound options.
Spellstone animatio nis now a green glow around your hands when activated.
Invisibility now causes the world to become wavy and the sky white, this includes Invisibility Potions and Cloaking Devices.
When right-clicking your portrait, there is a Dungeon Difficulty setting. (Has no effect on non-expansion instances)
There is now a black swirly animation when a spell is resisted.
The Quest Log has been expanded to hold 25 quests.
The Outland Map is now available on the map screen.
The Darnassus Alterac Valley Battlemaster has finally decided to join the other Battlemasters on the left side of the warrior's terrace.
All the starting area guards have had their levels increased to 65.
There is a courtyard door opened in the Undercity .
In order to make room for the new Looking for Group interface button, the World Map button was moved to the top left of your minimap.
There is a Silvermoon City teleporter NPC in the Undercity courtyard.
All hunter's pets have ben normalized to a 2.0 speed. (unconfirmed)
There is a new ship by Auberdine that takes you to Azuremyst Isle . Players without the expansion are teleported to the nearest graveyard after a certian point.
Reputation gained from quests appear in your general chat window instead of just the combat log.
Paladin Blessings and Seals have new animations.
Spellstone and Firestone can be equipped in the Wand slot.
The [Netherwind Mantle] has a new model, crystallized Banana Sundaes? (bug?)
Many professions that used to require a recipe, plan, etc to learn are now trainable by the corresponding profession trainer.
Spells automatically update on your action bar when new ranks are purchased.
The graphic on Hunter's Mark has changed.
A new sound plays when you are dazed.
Gouge and Backstab have new sounds.
Arcane Shot benefits more from ranged attack power. (unconfirmed)
Four new bank slots, and an extra gag slot that costs 25g to purchase.
The graphic on Corruption has changed.
New quests have been added througout the zones, including various Draenei and Blood Elf camps.
Many new items have been added to various vendors, including Jewelcrafting Plans.
New sound effect on Concussion Shot.
The maximum instanced PvP you can be in queue for at one time is 3. (bug?)
All class-specific spell books that previously dropped in dungeons are now trainable at 60.
Players can change their title from a drop-down menu to show their highest PvP rank next to their name.