Hey Jamie,
It's the famous Bart alright.
Hmm, yeah, I'd have to agree with Bel on his critique. Usually flattening stuff out will save alot of time and remove unecessary colors. Trust in your lines and let it suggest the shape instead of trying to build it with shades.
Also, in doing AA, there is such thing as too much AA! One could probably AA forever if given the motivation (you know.. AA your existing AA then another layer..). I usually try to use a minimum of colors to AA and the golden rule "If it doesn't make a difference (100% no zoom), don't do it."
As for the fixing the color: Maybe you could try using more variations of hue or trying a more saturated approach so it matches the cartoon. Right now, its kind of caught between realism and cartoony.
Lastly, don't forget about reflected light! Especially the grayscale version. (This is only applied if you're sticking to the realistic lighting approach)
