His legs seem to have a slight inward buckle. I dunno if that's purposeful or not, though.
The dark outline on the chestplate seems to seperate the cyborg arm from the body, and the pink midtone on the flesh makes him a bit less defined. Also, his head is either really small, or he's really tall...
As stephen said, the hair and pants could use some higher contrast, but overall it's looking good.
Keepitup.