Howdy,
I'm liking the style of this guy, specially the head.
Shape: Nothing to crit really, except for maybe that his arms are a little thin in places. Good job.
Colours: I think the jackets colours would look better if they were bolder and stood out. Raise the saturation a little to do this. Otherwise I like this, although his face is a little strange it could work.
Shading: This is where this guy falls down. You should read some tutorials on shading techniques. You can find great tutorials on dithering, and I think this is a skill that would greatly improve your work. The trousers look a little flat, and the majority of him is pillow shaded. Good job on the wood though
Peace,
B