One thing that stands out to me is the way you shaded his eyes. Maybe it was intended as some form of anti-aliasing, but it reads as shading, anyway.
Putting the shadow on the bottom of the eyes - assuming light from above - implies that the eyeballs are bulging out of their sockets. It would make more sense to put the shade along the upper edge of the eye, to imply a shadow being cast by the eyelid onto the eye. It's much less noticeable in Seiseki's edit where there is much heavier AA all over, but in your original pic it does look a bit weird to me.