Well, I'm not always the fastest, but meanwhile I have a theorie, what's the specific I like on this foto. Of course, I can say I like you, but it's quite usual that one likes the fotos of someone who one feels sympathy for. So that's not specifically nice on this foto, but a general thing.
This foto, however, combines two things: You seem to be relaxed and concentrated at the same time. And that's what I like, cause it correlates to my own nature. For many people to have to be concentrated means stress. But it's much better to concentrate automatically and with joy, cause you're interested in something. The instructor in me knows by the way, that this inner attitude is the best for learning successfully - to focus on something and to stay relaxed at the same time. Thus you even can learn without having planned before to learn something.
Was this a spontaneously snapshot made by someone else? It seems quite natural, not posed at all.
The dress is nice, yes, but I'm really no specialist on this matter. More important is, I think, that it's comfortable, as I read. I cannot understand why some people wear uncomfortable or impractical things just to follow some fashion. I myself wouldn't wear dresses (if it would be a option) - not enough pockets, you know ...