I agree with your note on the controls with the blocks. If I were to develop it from scratch again, I would use WASD for movement (the mouse movement is an artifact from an earlier prototype) and make the player snap to moving blocks (which makes sense, since he's grabbing on to them).
As for the music, I'm personally just happy that I wrote something at all! That being said, I initially wanted to write a song that felt more like a "sneaky ninja", but I was afraid of sounding like "stereotypical" Asian music, and I'm not a very experienced composer anyway. I guess a string quartet was just a familiar style that I could crank out on submission day.
I'll remember this feedback for my next jam. Thanks for the thoughtful comment!