Hi wonderful game!! Feel like Jonas' constructive feedback weren't very good. And I noticed so many things when playing it sorry.
In the first level. When you play the instruments with few notes. Like this one
You can get away with just timing, and then pressing Q, W, E and R. I like how the system is forgiving, but I think it is too forgiving in instruments with fewer notes
You could make it so that in instruments with fewer notes, you are allowed to do less mistakes. (Than the standard 4?)
Second, instead of exiting the Rhythm Panel when the last correct note is played; just allow the player to finish the last note. It'll make the player happier.
Third, when you play a note the entire screen bounces as positive feedback. I Instead of bouncing the entire screen just bounce the background. Bouncing the Rhythm Panel disturbs the player a little. <_>
Also since it's a positive feedback, I don't think the screen should bounce when you are playing transparent notes.
It's only because the game is so nice, that you notice these things. :)