Well.....
The anatomy is a bit long. You just really need to get your proportions a bit better.
The arms lack a bit of definition and your feet really need a bit of work.
The overall character design is a bit boring, The mask and clothing are the biggest reason that it is dull. They lack any sort of folds or wrinkles to make them interesting.
You have similar problems with the pose. It lacks dynamics. But at least I can tell you tried. You should have stuck her left arm out instead of her right since that would have added some flow to the picture.
I want to say that the lighting is bad, but the problem is that there is no lighting. You have some gradients going, but they are weak, and besides that, gradients are a bad way to shade. You need to plug in a light and get some real shadow cast on parts of the body, as well as some proper highlights. If you mix this with some good clothing folds, the costume can come out looking pretty decent.
I'm not going to go in to the background, I think Ash covered that well enough.