Very nice one button concept. I liked the fact that missed hits were recorded, i'm unsure whether they affected score but its great if they do.
The margin of error was rather large for hitting notes, a score system based on how precise you are would be good. I also felt like the notes weren't intended to be hit in time with the music, they felt a bit seperate and for a rhythm game I feel like this is important.
Otherwise, great concept and great game.