Well it isn't great, but for an impromtu shot it isn't terrible. The flash hot spot sucks, but it exposed pretty good on the model. The composition is too centered and too soft. She also has a classic posed smile that most women have for this type of shot--not your fault unless this was a formal shoot.
There is a thing called the rule of thirds in photography, in architecture and wood working its called the golden rectangle, and in other places its called the golden mean. Read about the rule of thirds which I think Rolando explains in the photo tips. I mention the other names in case your interested in all the places this rule pops up in the universe.
I'm not sure what is causing the softness, but it does appear you might have focused on her hair by her right ear. The focus should be on her eyes. Maybe some sharpening in Photoshop or other program will help, but you won't regain focus that was never there to begin with.
See if you can get her in a setting where you don't have to do impromptu shots and I'm sure they will improve dramatically.