It's ok.
The music is chill, the game pretty casual friendly.
My gripes with this game mostly comes with the OST. It's a lot of generic chillstep that's nice to listen to but doesn't really leave much of an impression.
And the backgrounds are really distracting x.x They're super busy and I found myself missing notes.

Maybe in future updates more songs will be added? I sure hope they update it because currently the game is bugged on chapter 5 where notes that should appear don't locking you out of getting to the end.