your goofing up the head proportions again =P, you seem to do this on all your models a little bit, but in this models case its a tad extreme, to the point its scary to look at =P/
you always seem to bring the jawline too far forward, and make the forehead too short, slanting back to the top of the head earlier than it should, making the face from the perspective and side views look a bit apelike,
bring the middle of the forehead forward a tad, and move back the face a little from the nose down. (you could probly cheap out and just whore soft selection here)
IMO, the chin pops out way too far, and for all the loops on and around the chin, it could be a rounder, less square chin. Also, his forearms are really tiny, as are the rest of the arm compared to the rest of the body. His build is slightly muscular, not scrawny ;p.
I think if you're going to spend that many polies on his face, put more into the nose. It looks like a box not a nose. Enix is right about the arms as well they're way way tiny compared to what they should be, but I'm assuming you're waiting to fix that till you add the hands. Also you might want to scale his lower body a bit wider, especially the lower half of his legs.
looks to me as if the head poly flow isn't correct. From the side perspective the head looks ape like to me.
Why aren't you using smoothing groops for your renders?
Well someone explained to me awhile ago that you add a bit of yourself when you model or draw something, because you are used to your own face and stucture, and I see a lot of lee in this model. Either that or he recycled the head from his self portrait model.
I agree 100% with enix, its a habbit I have myself when drawing, it takes a lot of effort to get away from it. Here's the problem, 1, you've got used to the same poly flow on your models imo, and it just wont cut it for such a chisseled character like Snake, he's got a lot of defining features and contours in his face that the poly flow has to match, I took the liberty of drawing out the main contours in his face for reference:
second problem is, if you look on the far right, that is the shape of a skull (placed due to your browline and skull width), unless very characterised and distorted, a skull typically will fit into a square from the side. Yours fits into a more rhombus type shape, of course this does depend on character, but snakes head is square and long, and his most dominant feature is his brow line, which is way too far backward in comparison to the jaw atm.
Take a look at some Kurt Russell pics and the original game art sometime, they're really great for refs too D:, the original game art really does well in showing the contours.