Yes, the hair on the cheek is a problem, also the red jumper is covered in bits of fluff which ideally need to be removed.
Whilst the direct flash needn't be a problem, you will get better results if you invest in a separate flash unit with a swivel/bounce head.
Otherwise, it's nice and sharp with smooth tones. Note that the image inspectors at iStock are quite creative types and shouldn't have a problem with shallow focus. BUT in my experience there is a difference between a picture being accepted and a picture that actually sells - you'll find that picture buyers generally prefer everything in focus.