I think the terrain it self looks really cool, but I would add some more decoration and details like different palms, and maybe dont make them all like straight, but this is only my opinion, I could be wrong.
Don’t make the island Square ish. Also, it needs lighting and more trees and detail. I can also see that the dock is a free model(correct me if im wrong) Use a few reference photos of real islands. Its not bad for a island!