There are three major flaws with the game:
1. When you start the game and it yells "SUPER MARIO GALAXY!" in the most annoying voice/tone possible...there's no way to avoid it short of muting the TV.
(It just makes me feel extremely embarrassed, even if no one is around)
2. The complete lack of camera control is some areas and levels...more often than not the areas that you could use it most. I don't understand why they didn't include camera control for all the levels, just in case.
3. The Boo suit.
Outside of those three, (the third one is debatable), relatively small gripes, yep it's outstanding. I loved almost every second of it.