Fun, but the start is very slow, and one or two more enemy types would be nice. Specifically there are no ranged enemies which makes it very easy to hang back if you get a ranged instrument. Towards the end of my winning run, i got a lot of power quickly which made the game go from "feeling so weak that the only safe way to deal with enemies was hanging back and spamming piano shots" to "feeling super strong" in just two rooms.
I'd say if you update this after the jam ends, buff the starting drums (perhaps by making aiming it easier) or let the player choose their starting instrument to ease the difficulty of the early game, and make enemies telegraph their attacks better. Enemies feel really unapproachable to even try using the drums