I think most of where it's lacking is in the head and arms. The perspective on the way the arms are sitting is a little weird with the way the forearms are overlapping, and that I can't tell which is supposed to be closer to the foreground and visa versa.
The head is a little weird, her chin seems very pointed and dainty, while her jawline is very blocky and manly. Also, her right brow seems to show the actual eyebrow and the actual build of a brow on her skull are sitting in somewhat different spots.
As for the twisted robe thing that's hanging there, it does need a bit of something to show how it attaches to the rest of her clothing. We, the viewers, have no idea why she's twisted it, so it looks out of place to us.
The torso and legs seem to be doing okay. Not spectacular, but they work. Her torso muscles look a little odd. It seems like you fit that muscle between her breasts and abs to the angle her breasts sit at for no foreseeable reason. Makes her build look a little reptilian or something.
That's right, Anon can give a real critique sometimes, rather than spouting "You suck, anatomy fail". I'm a fucking art student, and I don't care how good or bad an artist is, there's always room for actual constructive comments.