Holy crap mate... the hair is awesome, though, yes, it could use a few more highlights, other than that... love the texture you've given him, all the little details you added. Not to mention the awesome lighting scheme, very cool, with the one light from the back. Awesome stuff, Luxun, keep it up.
Damn this deserves more attention than it's getting. The coloring is gorgeous. I have been experimenting in trying to get a similar style like that. Like realistic enough that it would seem that it's popping out of the image. Made him even look more badass. As for criticism, I don't really got any.
i would like to see more highlights on his hair especially on (his) right side. perhaps also thee should be more varaition in tone on (his) left horn thig, it could pop a little more. Hwever the mood is very nice, well done Silas.