Well, I won't dwell on the meaning of the look in her eyes. It's different to view a portrait of a person you know and love and a person you've never met. I always recommend to look at your own work with the unprejudiced eyes of a stranger (if you can do such a trick). Only then you can approach evaluating your work without personal bias. There may be many different readings from many viewers, but rarely will all of them be same as yours.
As far as a formal quality of this shot (from technical and artistic point of view), without any personal slant, I can say this:
My position on the value of any photo is that the technique, composition and message must all come together to have a real impact on me (sometimes the message is replaced by a mood).
In this particular shot, I don't really care much about the technique. The face looks flat and almost featureless. The color is lifeless and unflattering. I understand, that in your mind it may fit your daughter's mood or state of mind, but still, I don't like it. The composition is not entirely bad, but could be better. In that matter I agree with Silas - about the distracting background and the shape of the frame. I think, square would work nicely here.
Well, I will stop here, because, as I said, without the element of good technique, there's no point to get to the artistic value. I know, I know, you can say that some great photographers take great shots seemingly without regard to good technique... But they do it entirely conciously and their breaking the rules of technique and/or composition is done in the way that amplifies the message or the mood. So, in a way, their technique is just right for their particular shots.
I always hope that my negative critique is not taken too personally. Please, don't get discouraged, Paul...
