Maybe a little more definition in the animation of the mouth, like animating the whole jaw while the mouth opens may make it look better. The piece as a whole is awesome anyways. So good job on that!
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But I think the facial hair could do with improvements. I don't like that moustache. 
Maybe a little more definition in the animation of the mouth, like animating the whole jaw while the mouth opens may make it look better. The piece as a whole is awesome anyways. So good job on that!