I wrote a fairly lengthy comment, but unfortunately itch.io seems to have eaten it. I'm trying to rewrite this based on what I remember.
The art is very nice, and the game overall feels polished and professional. The music is energetic and fun.
I found the game very difficult, though I'm not very good at rhythm games. I wasn't convinced about the genre mashup; it didn't really feel like a platformer and the rhythm game part felt weirdly disconnected. The notes didn't really correspond well with the music, certainly in terms of positioning and maybe in terms of timing too. The second (?) level was the worst; it had a part on the right that I'd expected to be a bass line but wasn't. While Melody bounces to the beat I never really felt like I was playing to the beat; I'd just move into position for the next note and time it for her to bounce into it.
I really wish itch hadn't eaten my comment; I know there were some good thoughts in it but unfortunately I can't remember them.