Eeei, circles! You do the whole "tinker-block" structure when you're sketching, just like I do! Yay! :3 My art teacher used to complain about that with my gesture sketches and stuff. o_O But pfft, I think it's an effective way to show the volume of the joints and all. :3

Anyway, I like this. The pose is very dynamic, he seems weary, like he's about to fall over from exhaustion. o_o Poor guy.