He's scary! I like what you have going on. All I can say is that it would help to establish how his weight is distributed in giving that real feel of the "shambling undead". His weight has to counter itself for his to stay upright, so if that leg can't have weight on it, then his torso will compensate by leaning the other way. Also, a bit of a forward lean gives things more intent (to harm) and adds menace.
I think this is great. Just play it up and act the character out on paper for a really striking illustration.
An open mouth and an open mind go hand in hand. - me