wow 624 that's a great poly count!! I love the legs and feet they really suit the character!
The one area that stands out to me most is the squareness of the neck and shoulder join atthe front. You could do with a poly split here and then move the faces back a bit to give a more rounded result.
Oh oh and make his forehead a little bit bigger (as in the drawing it's bigger and more pronounced) It reminds me of the brain from pinky and the brain!! (Which is a very good thing!)
Great work though I'm really enjoying it!
Technical Director - Framestore
Currently working on: Your Highness