Dithering lesson #1: use sparingly, and better not at all than too much! Here, only the dark green and dark brown dithering at the grass/cliff edge make sense. Maybe a little on the lower right cliff border too, not sure. And why dither air??
Lesson #2: beware of checkerboard flatness. See (in rock and clouds) how checkered patches only a few pixels wide create artificial flatness instead of the round transition you aimed for? These patterns must be broken, as narrow as possible, the effect of each single added pixel must be checked at small size (100 or 200%; if your software allows, open 2 windows of the piece, on to work and one to check). Besides, there is a lot of possible creativity in inventing different dithering patterns!
Lesson #3: dithering and anti-aliasing are the last things to do on a piece, almost together since they might conflict. This piece (as well as most pixel art) needs AA more than dithering. But before that, work on better composition, lines, colors and light. Not that it's bad, but it can improve ;)
The tree is too little and too centered and needs detail, clouds are a bit random, colors a bit sad.
I would expect the sky colors to be inverted, maybe it's me.
Hope I don't sound too harsh, I believe since you call it a test you expect feedback! Congrats for trying anyway, hope to see more stuff from you. Feel free to use the WIP forum too.
mm, never seen a floating playground before xD
great job with the dithering and shadows on the floating rock, by the sky could use some more dithering
you could also dither between two different shades of the sky to make it seem as if youre using a completely different color
like this: http://s68060.gridserver.com/upload/OIE_2910171_74452300/Untitled.gif
Thanks, and I was expecting feedback.. I took a look at a few peices of your art and it helped me understand dithering. I acknowledge you may not be the best but you're one of the best I have personally seen, I'll take advice on what you've told me and hopefully revamp this by tonight.
Otherwise. the tree is supposed to be that small.