I'm really bad at rhythm games, so there's not too much for me to say here. I liked the art and how the notes were presented-- had a way more relaxed vibe than other rhythm games I've played.
While I don't think the songs themselves were very hard, some of the notes seemed harder to hit than they should've been-- as other people have mentioned, the notes get kinda bunched up, which makes them a little hard to distinguish. Also, the timing for hitting notes seems kinda early. On another note, it was really hard for me to tell when an incoming note was supposed to be held. There's a visual indication, of course, but it often passed me by and I'd "miss" the holding-note because I thought it was a normal tapping-note.
In short, 'twas very cute but hard for me to get to grips with.