I think the problem with the hair is that it defies gravity...the curl in it could go behind an ear but I don't see one there...the flow of it looks like it comes from his face, round his head and down the neck...hang some stuff straight down through that curved area and see what it looks like. I agree that the back needs to be convex rather than concave. The hand also looks not quite right. Having said all THAT.... The lighting and texturing are spot on...it will be finishing off the posing that makes or breaks it.