Her eyes are incredible, and you light them just right so that they are the emphasis of this pic. Great even lighting. Her pose is a bit awkward, with her head looking like it's not attached, but just sitting on her shoulders. Sweeping her hair on the left (her right) back a bit, just enough to show a little of her neck, would fix that. And with the way her back is arched, showing her neck would give a really nice "S" curve to her spine.
Overall, great photo. Hope this critique helps. You're lucky to work with such a great model