I love it:
Music: It is in sync with the theme of the game, not forced (the only thing i would improve about that is having a second loop (file, as a toggle layer) as a fade out, so when you move to another zone it would fade out and then restart).
Gameplay: i like the way the different kind of instruments have it's own kind of "power", divided in different kinds of damage, so there's a good mix of strategy and player skill with the minigame.
Art: Definitely a strong point, solid art with each of the different kind of assets the game has. Some games have a fault in here that is that they use art from different artists, and then styles don't match, breaking a bit the inmersion experience. Your game definitely has NOT this problem, solid job.
And as for scripting, afaik solid as well, didn't find bugs for now, and if so i'll reply to this comment so you can track them :)
Good job! <3