#1: Can see end of the world, needs >>>more tile variation<<<. Trees are ugly. Also try to use growth better. And ofcourse needs fog.
#2: Again can see end of the world. Also needs better tile variation and better transition(if that's the good word), like from dirt - grassy dirt - grass. If you know what I mean. Also needs fog and, better use of growth.
#3: Grass used quite nice. But again the ugly trees... and the tree in front there is a piece missing... I can also see a seam in the clouds.
But overal, not a bad first try, keep it up and try to improve. Like #3 best, for the original angle.
Good luck and have fun terraining