Interesting, can improve!
There's an awful lot of banding: in the ears mostly, and around the face.
Here's an edit, probably far away from your intentions. I tried to break the symmetry a little with some very basic shading and highlights, added some AA, removed a lot of black, and changed one of your colors (the lightest brown, made to bridge between reds and browns).
Wow, I saw your edit and you're right, it looks much better in the face part... thanks!
I'll try and edit like what you did.