I'm not an advanced photographer by any means, but there are three things that catch my eye.
1. lighting: The shadows on her face don't seem to compliment her. she's very naturally beautiful, but there seems to be something strange going on there.
2. style: This is completely a matter of opinion, but this pic looks like she's posing for a yearbook, rather than being out to dinner with a friend.
3. expression: This kind of goes hand in hand with the last one, but she looks all business and the pose seems forced. Again, a matter of opinion. Personally, when I photograph out, I prefer the unexpected moments. I just did a shoot for a 33 yr old musician friend of mine the other day and the best shots I got happened by cracking a joke and catching her off guard. Gives the viewer more of an emotional connection with the model, I feel. But again, I recognize that this is all opinion based, so to each his/her own. I'm not on my comp with the photos, but when I am, I'll post one to kind of elaborate on what I mean.