I did like this. I think starting in C# minor, which is literally the best key signature known to man, was kind of a curveball for those who are less good at music theory. I think it should definitely start in something like F major of C major, since they're pretty simple (white/black basically). Other than that, the checkpoints seemed consistent until the last powerup, I would have liked to start there, not all the way back! Also, I think you can skip powerups... I don't know if that effects the game!
Other than that, that was pretty solid! Great job!