The outlines on the big rocks look good against the trees, but make the rocks look blurry against the dark dirt. Outlines should generally be darker than any of the abutting colours, or they create that blurry look. The solutions to this problem are to use your darkest background colour as the outline, or to not use an outline at all. I think the latter is the best option, since the other objects in the environment don't have outlines.
The dark, cool green on the prop plants looks a bit out of place with the rest of the foreground being warm. Consider using some of the warm colours from your grass instead - that way the plants won't pop too much, but won't look as misplaced:
Your floating rocks at the top and rocks on the side of the cliff and in the background rocks have some single-pixel noise you might want to fix. Also one of those flowers is totally floating off the top of the ground xP
I think it looks a bit odd that the background rock structure has warmer colours than the foreground rocks, whereas the rest of the background gets cooler the further it goes. Shouldn't the rock structure also be cooler if it's in the background?