The colors used are pretty nice, and the shading is average.
It seems clear that the source of light is on the top, but if you look things like the fist on the right, the "skirt" and those spherical things (I have no idea how they are called) the shading looks weird or just wrong.
The background works well. with the rest, but the pose is, not really comfy to watch.
It seems unbalanced and about to fall on the ground in any moment. The weight of the body just doesn't feel right. I suggest you to use a different pose, or, reduce the movement on the right.
Sadly, being a fan-art, I can't judge it from the point of creativity.