Really cool and cute game, I love the music, it fits the tone great and the character design is adorable.
I think mixing platforming and rhythym is a bit of a fools errand, so to get a game this good is impressive, but it's still problematic, hitting notes on time is really hard and so getting into the flow of the song is really hard. The pogo mechanic is a great way to mitigate the problem but it's still there, often I'm hitting notes way too early or way too late and while the game doesn't punish me for this, it doesn't feel like I'm actually following the rhythym and often I get thrown off for a later sequence. I don't think the problem is solvable though, and like I said I'm impressed it's this good.
Very solid little game, extremely cute, I enjoyed playing it a lot!