Pretty standard as far as platformers go, although I ran into issues that forced me to restart several times, mostly getting stuck in a corner grapple when I shouldn't have - once on the edge of movable boxes. Also on level 1 if you push the second box gently, you can't pass either way if it falls dead center on the button, causing a restart. The third time was again on the edge of a box next to a trampoline, causing me the lock up and jump up and down in the "holding" animation.
That being said, the graphics and especially sound/music design is very good. Really catches the gameboy feeling spot-on. Great job there! :)