I love it!
Well, it is! I was looking forward to this for a while and i'm by no means dissapointed. The learning curve seems just right and the way the levels and music changes as you advance are cool. You find yourself absolutely engrosed in the music and colours (no drugs involved). It's just like a visual LSD or something.
Like I said. i haven't played the PSP version but I know one thing. People saying it hasn't got some of the things that were on the PSP version I would say this... The Xbox Arcade version also costs a lot less and even with the advance pack it's still over half the price! Not only that it's multiplayer too.
Verdict: A very underestimated great game.