In particular, working on games, I believe (like with films), I don't think "release early, release often" is a good idea.
It might work with massive multiplayer games, where users tend to keep re-exploring the same content, but in general with games once someone has played a game once they don't tend to want to play it again.
I tried "release early, release often" with an iPhone game I wrote, and it was a mistake. The biggest problem is that users get angry if you take away, or significantly change, content from users. That's reasonable, but it means once you have added a level it is hard to take it away, even if you have a new, better level to replace it with.