The British author's erotic novel has been adapted by Hollywood into a film starring Jamie Dornan and Dakota Johnson as sizzling couple Christian Grey and Ana Steele.
During an appearance on America's Today show this week, E.L. James – who goes by the name Erica – said she was thrilled with the outcome.
"I'm very excited. I think it looks amazing. Absolutely amazing! I think the fandom will be very pleased," she said.
Erica admitted she had initial concerns about how the sex scenes would be treated on camera but she was "eventually" happy with the outcome. "I wanted it to be tasteful and I think after a lot of work we have it there."
"There is plenty of chemistry between Jamie and Dakota," she added, dismissing critics of thought the leads lacked heat after watching the trailers.
Erica said she was still overwhelmed by the success of the erotic trilogy, which was inspired by the characters of Edward and Bella in Twilight.
She added of her own storyline: "It came from lots of places, reading things, imagination, a little bit of life experience, we shall say…"
Erica said: "I'm constantly overwhelmed and shocked by the success of this book."
Fifty Shades arrives in cinemas this Valentine's Day.
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