Have a look at these references:
(I know you say those are older screenshots but I'll critique them anyhow)
Notice:
The bushes are green and in greater abundance
Cliff edges and rocks have hard corners, sand is curved and flowing (apply this to your last shot)
The interesting most interesting spaces are SPACES, they have verticality boundaries and changing widths, your map is too open in a bad way, there is little textures variation, the player has no direction or desire to explore, he knows there is no point walking in any direction because he can see everything in every direction until the map ends.
I'm not sure what gameplay you're aiming for, or if this is just an aesthetic experiment, but the goal should be part of your level design
Also consider a 2d skybox for the far off mountains, this is from a project I did recently with 2d and 3d mountains in the skybox, I made it and I can't even remember where the 3d ends and 2d starts
http://www.jordash.net/ROOT/2011_museum_3d/three.jpg I used the wall worm sky writer , 3ds max and extracted terrain from google earth to make it