I like those new colors. I might use them.
The shadows look really good, but I'd have to rewrite big parts of my engine to support it.
The varying tree color is a good idea. I might try it out, if I can get it to work in an auto-tiled environment. The dirt looks much more organic too. I'll have to try something like that.
Your sheep looks good, but too realistic. I'm trying to keep them less cute, more cartoony/stupid looking... Sort of a
Gary Larson thing. The "smart" things-- dogs and people-- can be more realistic

edit: Here's how the levels look now. I like the new colors. I don't know if the detail on the barn's front wall makes it look too "dirty"? I should probably up the saturation on the colored buttons and gates too.

There are also 2 variations on each tree and gravel tile, picked randomly when the level is drawn. There's still a strong "grid" to it, but that's hard to eliminate when I can't choose tiles manually. The only solution I see is to either eliminate all the detail (so that your eye can't pick out a repeating pattern), or create lots more variations of each piece.