There's only two things that I see; I'd dump the bevel completely (they always look fake), and the dunes in the desert seem pretty tall when compared to the mountains (I'd make them more subtle and lower). To get more height out of the mountains you might try doubling up on them. That will change the colors a bit so you'll have to tweak the top layer. But all in all they don't bother me all that much. Looks pretty good all around, nice job so far.