Your exif says you shot this at ISO 1600...that's way too high. For flash you can use ISO 100 to keep the noise out of your images...noise will decrease the amount of clean detail in your images.
Watch out when you bring in light from below your subject...it tends to make them have a surprised look on their face.
I know that you were shooting it in manual, but if you decide to use TTL remember that it works best at ISO400 or above indoors(or dimmly lit) and below ISO400 outdoors(or well lit). Just an fyi...
The first thing that I thought is that the flash has really picked out the stray hairs. Maybe next time ask your model to brush their hair?
Other than this I don't see anything wrong with it: it's a natural-looking pose, you've got a catchlight in the eyes, the lighting is even without being boring, and you've managed to make the model look attractive.