I agree, your colours look a bit dirty, and not as clear and sharp, most obviously the red on the skin, drybrushing should generally be kept away from as much as possible in my opinion.
You have an eye for picking out details, but what will help you improve by leaps and bounds will be to get away from the drybrushing and into layered blending. (we all go through the drybrushing phase, I just recently got out of it). Read the articles, they are TREMENDOUSLY helpful, and practice, practice, practice. Good luck!
This deserves at least a 5-5.5. The flesh work is pretty rough (unless he's supposed to have a rash) but there's highlighting and even some pretty nice reflections on the knife blade. A respectable first post :)