I really like the colors, but I think a bit more contrast wouldn't hurt.
I would make her whole upper torso slimmer, jacket and all. Either that or move the right arm closer to the body. I would also lower the upper torso a bit, but that's probably more of a personal preference.
The shading on the legs make them look flat, and she needs more knees.
Hips have been mentioned. Her waist might also need some work.
There's something odd about the way the shorts and the left leg meet. It also looks a bit odd that the waistline of the shorts is completely straight.
I also think she looks too happy for a ready-to-attack pose, but that might just be me again.

The pose probably needs a bit more work with regards to balance and such, but I'm not sure about that, so here's an edit with the things I mentioned to make it a bit clearer what I mean.

