I have to say, I really like this, for a combination of three reasons.
1) She's drawn accurately. Whoever drew this really knows their anatomy.
2) She has a very natural and relaxed pose.
3) She has a nice, calm, and confident expression.
All in all, it's a very well done picture. My only complaint is the eyes, which look a bit off. They might be a bit too big, but I'm not sure. Despite that, it still gets my seal of approval.
Edit: Oh, and the shading. Proper shading is essential if you want your artwork to look anywhere near this good.