Like mini said above, the amount of different blocks used makes the terrain look unrealistic. Choose a smaller selection, and make sure that the blocks used generally blend. If they don't combine and go well together then it won't look good. However making it blend into one color makes it have no texture. Which means you have to have a contrast of color. So how do you have to go around those two things? The amount of times used for the blocks. Don't make the amount of each block equal. Make more of a block then another. So what you would want to do is have one block type that's bearly used and is placed here and there. Then another that's used slightly more, and more, and more. Doing this will add contrast and texture, but doesn't make the colors blend. Using an equal amount of blocks that's distributed evenly makes it look funky. Add variation to everything. Remeber, nature isn't perfect and everything has to be inconsistent and consistent at the same time. (Sounds weird but it'll make sense once you dive in more). Also, are those trees just grown right in? If you're making your own build with trees instead of using plain ones that you can grow in try making custom ones. This makes the build unique and shows more effort instead of just spawning then in to get it done. In terms of the terraforming itself it looks great! It looks pretty well. I hope you use these tips for the build. Good luck! That is definetly a great start.
