I think there's too much busy texturing going on. For me. (I tend to be minimalistic, so take that with a grain of salt.)
Because all of the textures flat and busy from the front, there isn't really a sense of lighting, and so it almost feels like all of the duplicated trees are flat textured pieces of paper.
I'd tried to be more straightforward with where the light is coming from on the trees and reduce the overall business. On that note, I feel as a personal style thing that outlines - especially pure black outlines - should be reserved for important things, like interactive objects and physical platforms. Having every single background element outlined so starkly is distracting to me. But again, that's a style choice.
Love the colors! Keep it up.
