The tree is definitely competing with it's surroundings in priority and style. I feel they should be one in the same. The tree is the point of attention, yes; but it seems as if the tree is out of it's environment. The outlines, contrast, and saturation levels are what I think is contributing to this. Your treehouse has so much lively colors, hard (yet at the same time soft and fitting) outlines, and high contrast. The surroundings have low contrast, low saturation, and pretty much no outlines. The rocks that the cliffs are made out of look like clay.
Just seems off to me.
Anyways, I must let you know I love this. I love your style. And I'm liking how good you are at creating legit textures, again, such as the rocks on the cliff, using only some carefully placed, unrefined blotches of color. I need to learn how to do that.
