This is a great start on the diffuse work. It might not be a bad idea to make it a little more contrasty, but overall I think it's going in a great direction. Nice work.
Agree with Johny about the Normal Map. It looks great, but don't try to hamfist a normal map into this as it just won't look right, if you do go that route I'd keep it just for texture rather then trying to get the hipoly feel from it. But then at that point you might as well just bake it into the diffuse.
i hope you dont normal map this, since you should have made the highpoly first, but im really digging the difuse work, push it really to its limits and youll have a really good piece