If the idea is to fake a gradient, definitely.

If it is to texture, not necessarily. In this case you actually need to see it.

In any case, it's a pixel by pixel work: checking each one at 200% is a necessity. You want to achieve an overall effect which can be ruined by any single misplaced pixel.

What is most to avoid are usually isolated pixels (they jump to your eyes) and extensive checkerboard patterning (which creates unwanted additional transitions and planes instead of smoothing things; these planes are particularly nasty, because they appear perpendicular to the view: much worse than a solid color!). You have both of these! X/

Hmm, so I should really only use dithering when The colours have a fairly low contrast? Thanks for the tips, and I'm glad you like it tormi, thanks!

 This style is perfect! 

Agree with cure, I'd skip all dithering in this piece, except maybe in the lower sky. And even then. Everywhere else it is more of a problem than a solution.

Stubble would be ok too, only japanese have very little beard, usually only on the chin. Check some japanese drawings, there's lots on Wikimedia commons (keywords samurai or shogun).

Good composition, nice landscape.

because of how dark the purple is and how light the yellow is, the clouds look grainy along the bottom.

Ok, maybe I did over use it a little, thanks for the pointers. In regards to the chin dithering I was actually intending for it to look like stubble, what with the ronin being masterless, he's kind of let himself go. But you may be right on that anyway. Do you think there is anywhere else it is overused? Or is it the whole thing? Thanks again!

would advise not to use dithering unless you absolutely need to, and to keep it discrete when used (which is difficult or impossible to due with these challenge palettes). dithering on the face is too harsh due to the high contrast between the two colors used. dithering needs to be especially subtle if used on skin (which isn't really going to add anything at the size you're working at), since dithering adds texture.