Is this Stalin?

I agree with petrichor that the dithering gave your man a very wierd texture, but I also think it looks kind of cool.  Now if you were trying to make the skin texture look realistic, well then you kind of failed there.  None the less, while dithering can give unexpected consequences, its still kind of neat looking and you could remember this for when you want to do something with this kind of texture.

I think you could have made the skin pallete more interesting though.  You have this abstractish green background, blue hair and strange texture that treats the hair and skin the same and its all rather strange, but then the skin pallete is sort of bland.

and yes, some AA on the outline would probibly help.

I feel like it's important to realize that dithering doesn't JUST act as a gradient between shades--dithering adds texture. Pattern dithering in particular adds a ton of texture. It's made your man look as though he's made from sponges, unfortunately--and it'll always do that except when it's used extremely carefully and with an extremely circumspect palette, and from my extremely limited experience I would argue that it's harder to avoid the smaller your canvas.  I also feel like the eyes and the outer outline would have benefited from some AA--the blue from the hair would be perfect for smoothing out the eye.

Your lineart is obviously solid and your palette progression is nice, I just think you should take this as an example of how sometimes dithering techniques can have unexpected consequences :)