I love the player sprite. But the difficulty was really high for me and I wasn't able to finish the game. Bumping into the platforms above me and all of the leaps of faith were too much for me.
The atonal, chaotic music is very apocalyptic - which was fun at first, but then it got very hard on the ears.
I was playing on GBC and the shades of green that are used are very dark - it's actually not a very high contrast with the black background. You may want to tweak your color palettes for ease of visibility.