Im Not too Sure
This isnt Fine Art! Your peice looks much different the the other fine arts. Some of your other work looks more fine then this. But atlast I see where you were aiming for and it would be a super cool zombie If! it had one scab on his face. Maybe a bone showing and a rip in his hat.
Remember, Think Zombie! Just dont go around acting like them in your room in your Y.T. tightys. You know, missing clumps of beard, super dry lips, Shit A bloody nose!
I see you mainly focused on the hat and mouth. And the (my)right side of his beard looks perfect, but he needs a cheek bone on the other side, he looks half fat!
And please dont call me a faget. It only Damages your art.