Are you going for something stylized or a realistic human zombie? This would benefit from more geometry on the face. Now it's mostly texture that has very little information in it. Give him cheekbones and erode the areas that have soft flesh in the human face, like the cheeks. Give the areas of the face some contrast with varied levels of tearing in the skin. For example, give the cheeckbone area thin dry skin and strips of flesh holding the jawbone up. You could even expose some of the muscles. The eyes seem too close together, move them apart and put them deeper in the skull. Also ear looks small and misplaced, though i wonder what happens to an ear when it dries up, maybe it gets smaller
. Actually that would be a fun detail.
There's something i like about how he looks right now. He's a zombie, but not a zombie like all the other zombies.
Colors look good too and the lighting is going towards something real nice. Add some falloff for the light so that bright red doesn't continue that far to the lower part of the picture. Try a different hue for the implied details in the dark parts of the jacket.
Pose works. Jacket needs more work cause now it's a bit messy and doesn't conform to the guy inside.
