This is an amazingly innovative concept. It's been done before, but never to this extent and never in flash or puzzle concepts like theses.
I have a fairly decent computer and I feel like the controls and the gameplay is a bit slow and laggy. I'm unsure why this is, perhaps the tracking of all the motion in preparation for rewinding time? Regardless, I'd have a lot more fun playing this if it ran a lot more smooth.
The puzzles are excellent. I like the concept of the music picking up beats as you complete each puzzle... but I'm not fond of the music in general. It could have been way better.
Refine the heck out of this game, make the gameplay a lot smoother. Heck, find another engine to run / create this game on and you would most likely be able to market this to VALVe.
It's an amazing game with an amazing concept... but the graphics, sound, and control is just mediocre enough to make me not want to play this.