Hm, I'll give this neglected topic some crits.
Colors: The black as an internal color really isn't working here. It isn't working very well as an outline either, but that's fine for now. At 1x, the black makes the abs look like they're caving in or there's something funky on his belly or something. Besides, how does one get that much ab definition through a shirt? Loosen his shirt up a bit, use slightly less contrasty colors for muscle definition there, and it should look better.
If you're feeling adventurous, try some hue shifting on the skin. Right now, it's a mostly straight ramp and could be made more interesting by playing with color.
Shading: The legs look really flat, since they're shaded with the same value all the way across. The knee tries to give definition, but it still looks like a cardboard cutout. More on the knees later.
Also, make sure the head casts a shadow on the neck; it's not at the moment.
Anatomy: I don't claim to be an expert on anatomy, but here are a few things that jump out at me. Firstly, the head is very oddly shaped. I don't know anyone who has a chin that pointy; make sure there's some jaw definition. Also, he's looking very far up. If you move the eyes down, he'll be looking more forward. Giving him ears, hair, a nose, and a mouth is recommended as well.
The way his legs are shaded makes it seem that he's about to fall over backwards; they seem to be bent at a 90 degree angle. Fixing the shading to make them more cylindrical would probably help, but keep in mind that the parts above and below the knees would probably be lit about the same.
The feet look like stumps; give him some toes!
Other: Is he wearing pants? If he is, please make them a different shade than his skin. If he isn't, he must be a sad man in bed.
Overall, it's a decent start, but there's a lot of work to be done to get this looking good.
