All the attention is on the woman, and the background is inconsequential. The lighting is not harsh on Diana, it does not create deep shadows, but it is very soft all around her, almost blurry, but not quite, focusing the entire attention of the photo only on her. The depth of field is primarily her face and torso, the rest of the room is softly out of focus. The primary shape is Diana herself, slowly fading out into the background as she lies on the couch. In that, there is really very little sense of space, because the photo is so central to her, the space around her is not important at all. The first thing, and only thing, you see in this photo is Diana. She is somehow larger than life, even though she is portrayed so simply. There is strong contrast in the photo, because of the lighting solely on Diana, and the contrast is interesting and almost dramatic. There is very little repletion or pattern in the work, and that is not the purpose of this photo. Nor is there much movement present, it is difficult to take your eyes off Diana, so nothing else in the room matters. There is a variety of textures in the photo, from the strong, brightly lit Diana, to the texture of her top, to the soft, out of focus background. All that adds variety and depth to the photo, which makes it more interesting and appealing. It is also balanced and unified, so the photo really captures the woman and her feeling at the moment.

What does the photographer mean with this photo? It is clear. Diana was a great woman who most people placed on a pedestal, and...

She was beautiful, but troubled, and it shows in this photo. The photo certainly communicates beauty and wealth, the entire room screams of elegance, even though it is out of focus, but it also communicates social status and the prominence we place on fame in our society. Diana was glamorous and extremely popular, and so, the photographer wants to show society that Diana was one of "us," even though she was royalty. The way he shows her with no jewelry, just the woman herself, shows how he wanted to show her unadorned and "normal," without the trappings of a princess, and this works extremely well, making her seem more "common" and vulnerable, rather than haughty or arrogant.
This was a very public piece, used in the magazine Vanity Fair, and yet there is something very private and intimate about it, as if we have walked in and caught Diana in a very private moment. That is what makes it so memorable, and if any photo has the "plus" factor, this would have to be it. It caught a moment in time that can never happen again, and because of that, this image and all it conveys elevates it to greatness.