Missing something
This is a fun game for what it is but it's definitely missing something - there should be some way to be rewarded for a long streak, maybe a score bonus or something if you get 50 notes, 100 notes, etc. The songs could be longer too, it's difficult to get a high score because just as you're getting the hang of it, the song finishes unexpeditly.
Still, a pretty good well-made game but if you made some improvements, it would have been better (Headbanging Hero 2 *hint hint*)