Kickin' it ol' school?

I'm not very good at drawings, but here's my own personal input (whether or not it be correct or useful is up to the artist). I think you should continue the grainy look onto the head and hair, and make the neck a little beefier. The body is athletic but he doesn't have much of trapezes on the neck(that how they're called?), and the head uses color as its primary source of shading, making it look far smoother. In addition, the facial structuring uses smooth clear lines like in manga/anime, rather than the crosshatch style on the pants, making it seem like a drastic swap to a different picture altogether.

Other than that all I see as even a possibility for revision is the background that has a liquid drop effect which juxtaposes harshly against the characters angular structure.

Amazing piece