I have read all three books in the trilogy, Fifty Shades of Grey, Fifty Shades Darker, and Fifty Shades Freed. I initially bought the first book out of curiosity, to see what all the fuss is about. I had heard that the books were nothing but page after page of BDSM sex, and I was slightly disappointed when I discovered it wasn't page after page of sex until about halfway through the book. I dunno, perhaps the people saying it's nothing but sex are people who aren't very sexually experienced or are very shy and guarded when it comes to sex. Sure, there's a lot more sex in it than the average book, but there most certainly is a story line, and a pretty interesting one at that. The cliff hanger at the end of the first book is what compelled me to read the second and third.
Something that bugged me was how unrealistic the sex is. Ana, the main character, is a virgin when she meets Christian Grey and of course, he takes her virginity. She cums the first time they get intimate from no vaginal stimulation, just boob play. Then they have sex and she cums again. And all throughout the three books, she can orgasm literally on command. "Come for me, Ana!" Every time he tells her to cum, she does. Oh, if only it were that damned easy! Ridiculous.
it is an escape from reality. Christian Grey is this multi-billionaire playboy who showers his submissives with expensive new cars, laptops, phones, dinner, clothes, etc and is seemingly the most attractive man on the planet, with every woman who so much as glances at him blushing and stuttering uncontrollably. He is the epitome of a dominant, having a contract for his submissives to sign entailing rules including no eye contact, must always address him as "Sir," he controls what they wear, eat, how often and how long they sleep, when and how they exercise, what they drive, performs background checks on them, and does not allow them to masturbate either with him or without him.
In any case, regardless of it being unrealistic, it is a good read.