One of the best I've played so far. I would have preferred the controls zx to the numeric keypad if I'm using the arrows, for the sake of gameboy soul, personal preference, but other than that, the animations are great and the music+sfx as well.
A couple of things; Sometimes I would get caught while hanging like a bat. I do not know why. For long levels, I would introduce checkpoints. After the fourth restart it got tiring. Though, some or most of the GB were difficult as well, hmmm.
You did the "mistake" I did last year, while "emulating" the hardware settings. On the console, there is actually only one control for the overall sound. :-D