I'll be honest here, and leave a 30 32/50 rating.
The island design is rather underdeveloped and is quite blocky/cube-defined, so there's not much shaping involved. Ideally for a small build like this you should add more detail to make the terrain more interesting to look at, and less cube-like.
However, there are some good points. You don't limit yourself to one base elevation of terrain, and plop hills/etc on top of that, like most beginner terrainers will do. Your brickscape-cubescape mashup to slope up to the peak of the island is good, and shows your control over that skill. Also, unlike some terrainers (both experienced and novice) you understand the scale terrain exists on, and correspondingly don't jump or break the elevations in this build too much.
Just keep practicing; terrain is not something that's difficult to learn, just tedious to build well.