Great work!
The illustration is beautifully rendered. I can tell that a lot of time and effort went into this. I really enjoy seeing that in a piece of work! I have a few criticisms:
I believe someone has already mentioned the difference in size between his left and right phalanges. It's not immediately noticeable, but it is a subtle sort of nuance that gives the anatomy an awkward feeling.
His left leg (our right) seems a little naturally twisted. His knee seems to be pointed outward at too harsh of an angle, though this may just be my own opinion. I understand that has he walks forward, the leg that he is pushing off on, so to speak, fades into the distance, but there is something about the positioning that doesn't seem strong enough. It may be fading back too abruptly.
Other than that, it's a wonderful piece of work and will be a powerful addition to your portfolio!