This mirrors my own sentiments rather well. I've been waiting for Diablo 3 since...well... Diablo 2. Announcing one class at Blizzcon? No release date in sight? A testament to how successful they are, that they can announce a class for a game and count that as major news.
I shouldn't really complain; it is a convention, so it is mainly targeted to people who bought tickets and showed. I hear it was a blast from that point of view.