It’s a loaded question for me because I don’t think there’s anything special about it, not in any aesthetic sense. It’s the most popular, most expensive painting in modern history, so it’s special in that sense, but it’s just another old painting to me.
Leonardo Da Vinci, assuming he really was the artist he’s known as, was a talented artist, and it’s technically an excellent picture. But, when it comes to art, I don’t really hold portraits in high regard because they’re more about copying than creating.
Also, the girl in the picture isn’t physically attractive to me. She looks okay enough in the face, even without eyebrows, but I think she’d look a lot better if she were a lot thinner. And if she looked a lot better, I’d appreciate the painting a lot more.