Lights And Shadows
One of the things that I want to touch on it a texture on the cat its self. It seems so splotched together. Some fur texture would really help out in a lot of prominent places. Places like the ears, the brow and around the mouth come to mind.
That also brings up the lack or whiskers.Take a one pixel brush and make some real quick.
Another thing that would be nice to see is some more shadowing. You have some on the body, and a strong one at that, but not anywhere else. Some consistent lighting and shadows would really push this up a couple of levels.
The lack of any sort of contour lines make this seem very blobbed together. Even in art styles that have no line art, they still distinguish over lapping parts with a darker line. Not a black line mind you, but a line of a darker color. In a more realistic style of art, the over laps are usually defined by shadows, highlights or some sort of value change.
Going back to the lighting, I think some good strong shadows and highlights on the body properly mixed with a fur texture would really help this out. I can see that you started to push at that but didn't go the full mile.
As for the actual design and anatomy of the cat, it looks fine, well except for that elbow. For some reason it just seems kind of wild. The piece needs some over all refinement. Work mostly on your lighting.