DIABLO OWNS
for those who couldn't see the stream:
-Barbarian and Witch Doctor classes revealed so far
-Deckard Cain is back
-Uses battle.net
-Supports instant co-op matchmaking
-Has a skillbar
-Supports tab/mousewheel for quick swapping between skills on a mouse button
-Destructible environments (barb uses a skill that destroyed a wall and crushed some zombies)
-Enchantment system to enchant your weapons like in WoW.
-Monsters drop red orbs that can heal you.
-More traps in the game.
-Ladders that work, instead of loading a new map, you just traverse to a new area. Seems to be seamless.
-Also has female/male versions of each class.
EDIT EDIT EDIT:
http://eu.blizzard.com/diablo3/ <--- HAS GAMEPLAY FOOTAGE