Nice job. I finished the game and it felt very satisfying. What I think is lacking in the design is the distinction between notes. My strategy was to focus on each note at one time, and so it makes 3 distinct levels in one game if you get what I mean.
You mean the three colors of note? If so, your strategy is actually the one intended: focusing on only one color, and ignoring the two others (actually they become some kind of obstacle). This way bars are filled one at a time. Unfortunately I feel like a lot of players are trying to hit absolutely every notes (which is nearly impossible). I think I need to find a way to encourage them to focus on one color / symbol only.
Thank you for playing!