I don't think the guy looks bad, per se... but the proportions are out of whack. He looks like he would be a tall guy, so I think you should make his legs and torso longer. Also, the shoulders are really wide, they should be closer together.
Yes, the shoulders! They're the only thing killing it right now. I dig the cartoony style, especially in the head/face, but the anatomy could definitely use some work. Try bringing his shoulders in a LOT, and fixing up his right arm - the pectoral muscle should come in OVER it not under, as the shading suggests, and the elbow and shoulder are oddly shaped, being too sharp and too round respectively.
(also, to nitpick, his right hand is angled strangely - turn it a bit more toward us, the camera)