@Manjaman: Thanks! :)

@Manupix: Thanks so much for taking the time to help. Your explanation makes a lot of sense and indeed I'm glad you used your own piece (which is amazing, btw) and your own experience to explain. It's interesting to compare robnoyce and mierdinsky's work, because one makes exclusive use of the checkboard pattern, while the other combines a number of dithering patterns with some [carefully placed] noise. Lots to learn from those guys. Next time, I'll definitely try it out on a smaller canvas, so I can try to get it right. Cheers!

A few pointers about dithering:

One (old school) way to get away with a massive application is this: heavy transitionning between a lot of close colors. The low contrast steps help keep it smooth, and individual pixel positionning is not essential (I deliberately chose an early Jaeden piece, though she used progressively less and better dithering over the years, and not at all in this late piece, while retaining all the smoothness + badass clusters).

At the opposite end is this: the severe restrictions make it a necessity to 'add' colors. In this case it's of course useless to try to hide the dithering, but it has still to be made as acceptable as possible, and I have no idea how robnoyce managed it so masterfully. Pixel placement is  paramount, move or add or take one in most places and you ruin the piece.

Another example again: mierdinsky uses too much by most standards, but his placement is well refined. If you forget the noisy aspect of the whole piece and delve into details, many textured areas are gratifyingly balanced.

Now by contrast with these examples - ouch - your piece suffers of the classical dithering ailments:
- no 'new color' is added, except on the left side mountain and possibly the purple+green on the horse's leg, for instance the green+green doesn't look like a new color.
- no smoothness of transitions is added, instead it is as if new harsh edges had appeared (horse body). There are reasons for this: regular dithering patterns (checkerboard and derivatives) appear flat and in a plane perpendicular to the line of view, because we do see them as actual solid, flat checkerboards! So when you cover an area with them it necessarily becomes flat and oriented, and in a hard discontinuity with adjacent areas, either solid or patterned. Of course you tried to break this by varying the pattern, but this is really tricky, and literally each pixel has to be carefully placed after numerous trials and errors (and permanent checking at 200%). Very time consuming on large areas; you just can't rely on applying any set pattern. It took me actual hours to make it look right in the very small dithered area of this piece (sorry for self-ref, just convenient).
- Similarly, isolated pixels, and worse, rows of them, make terrible eye sores ;)

Hope this helps! Anyway, as usual I like the freshness of the piece and the nice composition. Also, best Hello Kitty design ever XD

WIN !                

Ah, how I miss the in-your-face South American commercials! Anyway, if you had a nice childhood with a proper upbringing, you should also have been reminded of this and this.

Reminds me of the commercial nissan car brand that is very popular here in Brazil, I think the damn pony.

 http://www.youtube.com/watch?v=X3yGSJE53kU

@jalonso : That makes sense. And certainly, I agree concerning its difficulty. As I keep experimenting, I'll hopefully develop a sense of what it takes to make it work. Meanwhile, I'm open for opinions on where I've gone wrong.

Dithering works when it dithers (blends,smooths,softens,creates) not when it just makes a pattern/shape/area.

Dithering is the simplest PA technique yet the toughest to do right.

@Darken: Thanks for your comment! I understand what you're saying, but I don't understand why it's like that. I mean, do the "thick" colors (and I'm not sure what that means) not work well with dithering? If they do, have I chosen the wrong dithering patterns? Sometimes, dithering is simply used to create new shades, but sometimes it is used to create depth. If I had done the entire pony in a checkerboard pattern, wouldn't it be too flat?

I keep seeing people comment that dithering is "over-done", but it doesn't make sense to me. Some pieces are almost 100% dithering (and some are indeed 100% dithering), but end up looking great. Clearly, it's not a matter of getting the right amount of dithering, it's a matter of doing it well, and getting the dithering to work with the shapes, colours and textures.

EDIT: I'm obviously not saying that this is well-done. I'm just trying to find out why it's not :)

"but it might have been too difficult due to the limited amount of colours"

 The point of dithering is if you have a limited pallete and want to create a brand new shade, tricking the eye. The dithering here is over-done and gives the pony a snakeskin like texture. Notice how the right mountain looks better than the left mountain. The shapes are more defined and clear. The strength of this pallete IMO comes from the thickness of the colors, like the rainbow or the trees that you did. Those look fine.