Some developers put out a date, only to keep pushing the date further ahead so they can get all the kinks out. That's much better than releasing it and having people complain about all the things that are wrong with the game. I wish more developers took the time to do that. It's a win for both sides. Developers can get better reviews, and the customers will be happier with the game.
It IS kind of annoying when a game keeps getting delayed, though! I mean, sure, I appreciate they are working out all the kinks before release, but sometimes it just makes me think they announced the game too early and should've waited more time.