Yeh, he does look a bit squat. Try bringing the elbow down to the hip, then making his forearm a wee bit longer than his upper arm (from bottom of shoulder to elbow). His open hand should come down to almost the knee (a little above it) and the thigh should look natural. Then the shins are just a bit longer than the thigh (but not a lot) and that's about it. I try to think about the divine proportion of Phi discussed in DaVinci Code (most popularly) and elsewhere: 1:1.618. The upper body is in a ratio of 1:1.618 with the lower body, the thigh is 1:1.618 with the lower leg, etc. It works pretty well.
Also, the head looks inflated and kinda detatched from the body. An erasing, downshift, and downsizing of the head would do it.
But I love your shading. Seriously, it's my favorite part of your work, and I wish I could shade half as well as naturally as you do.