I find all of the reviews of the Fifty Shades trilogy amusing. I read the first book and enjoyed some parts of it, but I certainly do not think it is worthy of any kind of "literary" rating.
Let's call a spade a spade - this book should only be read for the sex. Similarly, a porn movie should only be watched for the sex...the acting is terrible, the storyline is terrible, the characters have no depth, the presentation is sub-par etc. etc. I have never heard someone compare a porn movie to a real movie. Why should we expect the characters in Fifty Shades to have depth? It is, quite simply, not that type of book. I have no idea why anyone would attempt to rate this novel based on literary standards. It is what it is. And that is ok.