Quite possibly perfect.
Where the music is concerned I must admit I'm not that impressed with the remixes. I've heard the mario theme done a million ways already and the songs from all the different versions (2, 3, world, 64) make their appearance here. Its the original tracks that really stand out for me not to mention the subtle touches where sound effect feedback and progress through the game changes the music. For instance, the waltz while on the Luma's comet builds becoming more complex as you collect more stars. And the galaxy selection screen which beeps at you as you run over a potential galaxy changes the pitch of the beep to fit the chord of the music playing. The original tracks span a wonderful gap between fully orchestral to well executed ambient electronica (and just about everywhere in between).
Personally I find the story to be quite touching. It take a real serious turn at the 'Telescope' chapter. Well, serious for Mario. But it sure had me caught off guard. It's important to remember that you don't even have to partake in the story if you don't want. Just stay out of the library.
My one complaint is that the 2nd play controls turned out to be quite boring. I half expected that but the extent to which they were useless what not appreciated until I tried them. There just isn't enough for the second player to do when they aren't in control of Mario. But no one expected Mario to be the next great multiplayer game anyways so that's hardly a problem.
Bottom line: a seamless integration of control, graphics, music, sound and mind-bending gameplay that will entertain long after it has earned its keep.