Two things - It's a bit dark but that's fine. But you do have light hitting the background off to viewer's right. I'd be tempted to clone all of that to dark.
Another way to improve this is to get catchlights in the eyes, or at least one of them.
I'll agree with others about the background. The light coming off the edge of the chair is, for me, very distracting. Other than that, I like the amount of light on the subjects face.
