Hey there!
Its alright, But some of them need a fair amount of work, I'll review them step by step
Pic 1 - Its a good idea, but some of the doodads just don't fit, I like the way how you put the (supposed to be a squirrel I would guess xD) On the tree, but it just doesn't fit in with the rest of the "death" scene... Remove that and add more tile variation and it will look a lot better.
Pic 2 - Also a nice idea, but it would look much, much better if you would use the "raise terrain" tool, not the cliff tool, and add a lot more waterfalls to make it look more realistic, you can see the ground underneath them. Add some rocks and water life, and it will look great.
Pic 3 - This one needs a fair amount of work, I can give a fair few tips - Zoom the camera out, add some shells and seaweed and other plants, and perhaps some fish... And the major lacking feature in this is atmosphere. Try to use terrain fog to make it look like your actually underwater, Terrain fog will give everything a tint, and if you set it to the right colour and distance, it will look exactly like water.
Pic 4 - This one is my favourite, because it looks the best (in my opinion) and doesn't really have any problems. Nice use of the UTM doodads, but as Ghostwolf said in the chat before, the scene is missing something "living", such as a dog on the ground, or a peasant standing against a wall, or something around those lines.
All in all you've done a fairly good job, is it you first go at terraining? If so, its really good
Hellblazer-14