inb4conan 
FFUUUUUU
35/50
note: the above score is based on terraining skills shown here
this looks perfect for an additional island to pirate DM but otherwise not that great in any respect
main hill of island sticks out without any sloping at all and is pretty unrealistic; green blocks eh. it would be better if you kept them grey and added green bricks on top of the cubes to emulate grass
Points for the plating detail and studding; I'd never expect it to work out so well with this style of clean cubescaping. the breaking up of the top surface of the hill also gets points.
i'm assuming you can do better but just didn't; from what I can tell here it looks like you can. but looks can deceive.
The island in the background of the second shot looks a lot better but lacks underwater sand sloping (terrain doesn't just drop off after it disappears under the water). its somewhat more basic than yours though.