Pretty good!
Nice structure and quite good shading. Proportions seem to be a little unintentionally off (i.e. knuckled too thick, eyes not quite in the right place on head).
Having said that, I'll watch what else you submit with interest.
(or at least, I will once Newgrounds allows me to look at my art reviews on one page or lets me subscribe to people a la Youtube & DeviantArt)