I guess I'll go ahead and critique this since I love it so much. >u<
Pros: The background coloring is nice. It's nice and bright. I, personally, would tone the intensity of the color down just a little to make it seem more natural, but it's fine as is. Also, this is absolutely ADORABLE! >U<
Cons: The tree could use a little more texture. Try out different brushes and see what you can do! Also, I can't give you much of a score in the originality section because you used another piece of art for a reference. It's usually better if you don't use reference photos too often, and just for practice, which I believe is what you were doing here. The anatomy could also use a little work, but considering the pose, it's pretty good.
But, it's a bit plain looking. try putting in more textures on the bark, or try making leaves. It really adds impact to the picture.
The clouds look a bit blurred. try making them look more defined.
The tree itself is a bit unrealistic. The tree looks a flat, and the branch is coming out at a sharp angle. And what about the leaves? leaves are difficult, yes, but they would make the picture look about 105% better, trust me.
The shading on the tree is nice, again, it could use more texture, but it looks okay. Work on WHERE you shade though. not just the edges of the tree should be shaded. The shading on the cat though, i think that could be darker, to match the tree. To be honest, i cant really even tell that its shaded. It looks flat, like a drawing with markers. Give it darker shading, and put it in the right spots, and there will be more dimension to it.
Your anatomy could use work, but then again, this is quite alright for a difficult pose.