Its very heavily dithered, too heavily dithered, making it look too grainy. I would try using smoother blocks of colour with a few more colours for AA to smoothen the image. I think you could do away with at least 1 of the blues you are using, probably 2 or 3 even. You could probably do away with that black in his eyes (is it black?) and replace it with the dark brown, or the very dark blue (which I probably wouldn't keep in there actually).
Besides that the lineart is quite nice.
