I think its going to bring alot of life back to the old world of azeroth which will be great.
Redesigning and adding new, better and more streamlined quests to the old zones is going to give many players reasons to reroll a new character.
I think its good that they didnt decide to put in a new class, it does affect the balance of the game by alot and they end up spending the first few months of the expansion just trying to get everybody back on an evenish level.
Worgen sounds like an awesome new class with decent racials. Goblins sound like they have awesome racials too but as a race i think i would just be annoyed if i had to hear those voices ALL THE TIME. (i hate going to the banks and auction houses as it is)
Flying in azeroth will be a nice feature, but I dont think its cause to leap around with joy.
I wish they had upped level cap up to 90, but hey 85 is good enough i spose.
I am really looking foward to rerolling a new char in the expansion, (possibly a worgen).