First I want to say that this is my first post, no excuse but I'm a little scared. xD
Anyways, I couldn't really decide if this picture was finished because my understanding in colors is just starting to grow. Maybe you guys can help me with some improvements?
The picture is inspired by characters in Left 4 Dead:
you're modeling with really soft brushes. This, of course, gives you nothing but soft edges and loses a lot of depth. Check out the "edges" post Elwell has up (it's either in here or the WIP forum).
There's not a lot of anatomical sense. Your figure is made up more or less of blobs- which I understand you're going for, but I don't get a sense of how he moves and all of that fun stuff.
When you color, remember warm and cool. It looks like you stuck with the same hue here and changed your values. I'm sure we all did that at one time or another (I know I did), but you should start thinking in warms and cools. Only through painting from life will you really start to understand this... the presence of light warms things up and should leave your shadows cooler. Try not to color with black as general rule... it's the most de-saturated, low value "color" and it really flattens your image. Also kills color vibrance. Yeah. It's just a lot of soft edged black...
Keep posting and work on your life drawing.