Let me say right at the outset that I usually find fault with flash used in portraiture, because it is usually too harsh. In most cases where flash is used it seems to need more diffusion (bounce from umbrella or ceiling), greater distance to the subject, etc.
In this case one can see bright areas as follows:
- a line across the lower forehead,
- a vertical line down the center of the nose,
- a bright spot right on the tip of the nose,
- and finally, a minor spot in the center of her chin.
Mind you, none of that is all that bad - it's just that otherwise the picture has good lighting, the backlighting is doing great things with her hair and the composition isn't bad, considering that that was probably not your area of concern on this shot.
My point is that these artifacts that are easily recognized as unique to use of flash are in fact somewhat un-natural and would not be seen if the lighting were from a more ideal lighting, such as open shade.
A separate issue is the backlighting, which is doing great for the hair, but is nonetheless providing too much white in the background, in my opinion.