Proportionally, his legs are a little short, makin' him look frumpy. As far as the arm, i'd probably pull his elbow back, making it more linear. The top half looks pushed forward while the bottom doesn't match it as well.
Want a good read?
http://www.amazon.com/Figure-Drawing...figure+drawing . Andrew Loomis is B.A. and has a few reference books out there.
I love your coloring and would love to see you make a trippy adventure comic someday