Very nice, you did an especially good job on the hands. Your proportions are also looking pretty good. I like it!
Edit: whoo, confusion. On my part. I was going to say the perspective on his face is a little iffy. This is true on the cheekbones, and not his nose like I thought at first. What's really confusing me about his face is that the line defining his jaw closest to us shouldn't go straight up into his cheekbone. Continuing the line a little further, then curving slightly up without completing into another form should fix it. I think.
Other little things, like the continuous line around his face, and the left side of his jaw (our right) continuing a curve down his neck make his face seem flat in comparison to the rest of the the picture.
The last little thing would to be to go in darker with your colored pencils and vary your values more. You'll get a greater sense of depth and your highlights will pop out more.
You've obviously got a lot of potential drawing figures, so keep going! You're doing a good job
edit: My figure drawing classes must be melting my brain