The mountains are too low poly they look bloby. At least get some normals and displacment maps in there.
You have highlights and midtones but there are no dark spots, contrast works wonders.
All the colors are too close together in shade, It looks like you're going for an american type desert, the rocks have more orange in them. Shrubbery and grass can also still be muted grrens although not all the time. Overall the color is bland and washed out.
Make the time of day more in the afternoon or in the morning to get better shadows. This perfect high noon looks unnatural.