Well... where's the claw? :)

I quite like this, but I'm having trouble making sense of the head. At first, I thought the yellow was the mouth. Now, I think it looks like a moustache. The lower half circle might be a chin, but it could also be the mouth.

Try to exaggerate the highlights and shadows. For example, you could highlight his wrinkled brow, and put shadow underneath his brow. You could add shadow underneath his moustache (?) and directly underneath the wrinkle of his chin (?).