actually this could be criticized.
First off, the shading on the head is too bright between its colors. go for a darker shade but not too dark. You want your shading to look as its reflected by a light source (like all sprites do)
Second, your shading isn't correctly where it is. Your body shading is centered around the middle. If its a platform sprite, it has to reflect from the platform sprite's POV (Point of view).
http://www.pixeljoint.com/forum/forum_p ... ?TID=11299This tutorial should help you alot