This was fun! I like that to get "perfect" you had to hit the note on the beat, and I wish that was more of a requirement in general, mostly because (for me) hitting the notes on beat is the most satisfying part of rhythm games. I also really liked the art (especially the running animation), although more cohesion between art styles would've been nice.
Update: I was actually wondering if you'd be willing to share the running animation sprite sheet with me! I haven't done a running animation before, and I think it'd be a really good reference point. If not, no worries - I figured this was the best way to ask.