Well, she's stunning - and I really like the lighting. That's the good - the bad.. eh, not real sure. The pose just seems a little.. I dunno, off. Ok, granted keep in mind I don't do a lot of people portraits or people posing - so I am absolutely by no stretch of the imagination an expert on that subject, about as far from it as you can get really.
But at least to my untrained eye - well hard to put into words really, I guess maybe it's the position of her head. Ok, ya, that probably was not as helpful as I would have liked but best I can do at least for now. Sorry.. lol
Quick edit...
Ok, looking at it again.. I guess the word I would use to describe her head position would be that it almost looks strained - maybe by dropping her chin a bit it would make her look more relaxed. Hope that made at least a little sense.