This book cover image provided by Vintage Books shows "Fifty Shades of Grey," by E L James. (AP)

It won’t just be women in that line either — the Associated Press reports that the book, which explores a relationship between a sexually-dominant billionaire and his virginal, submissive mistress, has been winning over male fans, as well.

“Most people who criticize it haven’t read it,” ex-Marine Bob James, 50, who is not related to the author, told the AP. “They take things out of context and just pick the sex scenes out. I liked the romance. Ana is drawing him away from all the bondage stuff.”

Many of the fans of the book have bought it as an e-book, which offers more discretion for those who don’t want a telltale cover to give away the fact that they’re reading erotica. Though it seems like it could present a problem bringing an e-reader to a book signing — what can the author to sign, the cover of a Kindle? — Barnes & Noble says they’ll also offer a limited quantity of collectible cards for James to autograph for people who bought the book on an e-reader.

Most critics, however, remain steadfast in their belief that “Fifty Shades of Grey” is pablum, despite its mainstream acceptance. James wrote the book as “Twilight” fan fiction, and originally put it online as a free download. As it picked up steam, it moved to a small Australian publisher, then to major publishing house Knopf, where it has since become a bestseller.

The Post hasn’t reviewed “Fifty Shades of Grey,” though. Washington Post book critic Ron Charles said he tried to read it, but couldn’t continue. “Sex has never been so dull,” said Charles.