I really like the art style! really original concept!
The solos were you complete and instruments are nice and satisfying.
The band song was really good too :)
Feedback (I hope here is an appropriate spot, I can delete it):
The drum level was too confusing for me, had to do it 4 times, maybe combine a few of the drums into 1 part, like the base and bongos, or after finishing reset the wrong parts and keep the right one.
For the tuning levels, I think if you'll make it that space bar or some keyboard key will be play instead of the mouse, it will feel more fluid instead of going back and forth with the mouse.
The song need to be less difficult in my opinion, consider adding some visual effect when the note is played right.
minor bug: after the game is finished if you click on parts of the screen you can go back to the tuning scenes.