This is nicely done. I like his obvious hooked nose and his great Snapish hair. Awesome scowl/expression and brows. ^_^
A suggestion: I don't know if the blue and purple is intentional or just the result of the photo/scan. If it's not intentional, have you considered punching up the contrast, fooling with midtones settings, and making it greyscale? Such things can improve the general appearance in terms of quality, if you happen to be going for something sharper. Many programs will allow you to do this.
In this case the purple and blue were intentional, however, I do feel that the quality of my work would increase quite a bit if I were not taking pictures of my art with a web cam, and instead using a scanner. lol