The contrast for his hair is not good. Add 10 or so and it'll look great. Oh and the belt strap needs changing too, in terms of shading and of design (the whirl!). Yeah, this is basically what Blackdragon said...

not bad, it disappears against PJs Background though.

You actually missed alot of the detail in the cell shading. If you notice the shading follows the lines of the clothes with spikes of shadow. Looks a bit unfinished to me. Check out some tutorials or tips on AAing, i'd suggest. :)

Ah, before I forget: the outer AA ruins the picture if its on a dark theme (we can change the sites colors)

So remove it or put it on a white background.

More contrast in the yellows would be nice, and desaturate it a bit. And maybe AA.

Sweet hair blowing in the wind animation :D

You missed the little twirly wind symbol on his belt, otherwise this is nice.