It's hard to critique it, because I know I couldn't do make it (at least not at my present level of skill. But I won't let that stop me :-).

Given the broadness of the shoulders the chest should probably be broader too. Also, the muscle/artery in the neck looks like it's going over the color bone and the back/neck muscle (trapezius?) sits pretty high.

Here's a photoshop modification to show what I mean.