I think this is all around a really very nice portrait. The colours are fantastic, I really like the composition; her position and expression, the glasses, the contrast of the deeper red of her lipstick. The depth of field is perfect in my opinion. Professional photographers always go on about photos needing to tell a story, and this is one of few photos I've viewed that I really get that feeling from. I am a big fan of this photo.
The bright red of the model's lipstick contrasting with the slightly muted colors elsewhere is great. I think, though, that what really makes the shot is the look on the model's face and in her eyes. A wistful melancholy.