Yeah, the gradient adds a lot of colors but I also think it doesn't make it look too nice. I think you can achieve the affect you want with less colors and make it look nicer than the graident.
the sprite sheet is nice. but it is too much gradient, XP.
http://hivemind.in/pj/specs/index.php?urls=http%3A%2F%2Fwww.pixeljoint.com%2Ffiles%2Ficons%2Ffull%2F5__r1730457971.png
a lot of yellow tons.
You don't exactly need to to dithering. All you need is a bit of AA to make the shadows more smooth... then BAM, you got it! :D. Either way, this piece does have good design.