I really like the second and the last picture. Are those custom rocks?
IMHO, the green and red clash too much. Like the fourth pic with the tropical trees and sand next to lava looks a bit awkward.
I don't think anything is custom. I'm not sure if I imported those trees, probably not. I did play with some settings though - the waterfalls work backwards.
The clash could be inovative, but atm there is not really alot to talk about, still very plain and empty, but for a gameplayable map the terrain does not look bad so far.