Man, was that one of the best games I've played in years. It's definitely up there with Super Mario 3 and even the original. You can tell they weren't going for a quick cash in with the mario name. I have to say, this could be the best platformer I've ever played.
Anyway, for anybody who hasn't beaten it, keep going! The last few galaxies are so fun. The last level and then the boss fight are definitely the best parts of the game.