Having never watched the show, I can say I think it looks good. Face seems to look like him.
As for how to shade cartoons. I'd just leave most if it flat, smooth the outline a bit inside the coloring, and maybe add basic large shadows. Like a shadow on the neck from the head. Maybe a shadow on the torso near the arm pit area. Cartoons usually don't have a ton of shading unless it's a dramatic shot, or something large casts it, like a tree or building.
You could also look at Anime as an example for shading. They use shadows a bit more than western cartoons.
I think the only cartoon character I've actually made a Micro of is Ickus from AHH Real Monsters. Closest other than that is a bunch of Naruto Micros that I shaded a bit too much.