Everything I hear about that book is more of a "so bad you have to read it just to believe something that lame can get published" kind of deal. Imagine starting with Twilight fanfic that's bad even by the standards of Twilight fan fiction, then make it even worse. Literally, like the wiki claims that's what it is. It started as Twilight fanwank. No joke. Mix in protagonists that are somehow even less likable than the source material and season liberally with what we're supposed to think is BDSM but is instead crude violence and unambiguous abuse. Garnish with a character arc that centers around romanticising a toxic relationship with a full on rapist and trying to save the abusive bastard from his own assholishness, then very suddenly and in defiance of human psychology succeeds. Voila. A perfect crock of shit.
The whole thing sounds like a peek through the eyes and shattered psyche of a battered woman who never shook off the idea that she'll eventually redeem her abuser if she weathers the storm. That quite possibly says some dark things about E.L. James.
(I'm just guessing here but if the story ended with Christian Grey still an unrepentant bastard the book wouldn't sell nearly as well. The idea that you can find the good in someone and redeem them is what traps a lot of people, both men and women alike, in abusive relationships and they convince themselves that if it pays off everything leading up to that salvation can become water under the bridge. Everyone knows someone they wish they could save. Everyone. Nobody wants to face the reality that the only reasonable thing you can do is walk away.)
Like Twilight itself I'm pretty dumbfounded by this drek's popularity. But also like Twilight this maggot ridden pile of reeking garbage is fantasy and things we enjoy in fantasy don't translate to real life. How many men fantasize about being action heroes? How many would be scarred for life actually surviving an onslaught of terrorists/ninjas/zombies/aliens/etc? Valid observation, wrong conclusion. A fantasy will never not be on your terms. Trying to enact this in real life and forcing your will on someone else is a horrific thing. It will be met with resistance, and it will end either with the perpetrator suffering their comeuppance or the victim - and victim they would be - a broken human being.