to bulgy        

Desing is good. Get rid of the pillow shading as the guy said

I'm diggin' the design, looks very Mega Man X-ish. I've got a couple constructive comments though. It looks like you didn't decide on a light source for this picture, because the shading all looks like "pillow" shading (everything is light in the middle, and gets dark towards the edges). You really want to have a clear light source and some shadows. Lighting is one of the most important parts of any form of artwork, since the human eye is very good at interpreting light and shadow, and is difficult to trick. Also since this is a metal character, he could use some highlights as well. I see a couple in there but you can go a lot more extreme than that.