Ear seem too big, globby, it's over AA'ed as well. Those lips would make Angelina jealous, and no I'm referring to yer snapshot, calm down. The eyes with pupils are too defined, Accident had it done better, but also made you look too much like Chino Moreno. Shoulders seem off-kilter. Forgive my absence of an edit. Honestly I don't feel compelled enough by this to create one, but I at least had some crittely crittely crit for ya. Like your out-on-a-limb palette. You should continue to play with it, it's not perfect.
. . . uh oh, with my Vista Windows cursor reverted back to the classic theme hovering over the "Post" button it suddenly hit me why this portrait is not working. You have a conflict of style's here, and peace negotions are resulting in even the opposing sides' diplomats getting into a fist fight after only moments of negotiations - You're doing the vexel style (like Panda) yet your excessively dithering. Vexel style is simply pixel art mimicing simplistic vector art, having very defined egdes, very crispy AA, no gradation, etc. What I'm saying is, I think that if you removed all dithering and only used "solid shapes" to define your volumes you may have yourself a humdinger here. End the conflict. Just do a quick dirty test, should take 1 minute to do, just to see if it "feels" right. Oh, and this portrait probably needs sunglasses and a poka-dotted bow ribbon in the hair, essential accessories you know.