This piece is quite adorable, I love the little kitty, what a cutie.
The shading and the color choice in this piece are absolutely wonderful, however, there are a few anatomical errors.

A problem that sticks out almost immediately is that her right shoulder (the one closest to the viewer) does not appear to be connected to her arm due to the way you drew the arm itself. The top curve of the shoulder should also be a part of the top of the arm, and that should help fix the error.
The other anatomical problem is that her legs appear too short in comparison to her torso. What I have noticed is that typically the legs are approximately twice the size of the torso, with the knees being almost directly in the center. It helps to just check the distance with your fingers to make sure the legs aren't too long or too short.
Also, the feet should be a bit larger, since the foot should be almost as long as the lower arm.

Other than that the piece is very well done, and you have quite the cute style. Great job!

The colors in this are beautiful and each one seems to flatter the other, leaving no hue gaudy and out of place. Your use of bold lines succeeded in accentuating the characters and was further supported by the muted, line-less background.

While my positive remarks shine bright in this piece, they are not enough to conceal a few gaping flaws in the girl's anatomy. The first error is in her upper right arm, where her humerus and scapula seem to have zero involvement with each other. The arm should protrude from the shoulder so as not to look detached. Also, the shading on her knee-high socks does not support the breadth suggested by her thighs. The hollow shading makes her legs look crippled and/or non-existent.

But to sum things up, this is still a lovely piece and the mistakes can be easily corrected.