I read The Devil Wears Prada. I knew it was awful but I didn't realise how awful it could get.
Yep that's another one where I quite enjoyed the movie (in a light, fluffy sort of way) and decided to read the book, and couldn't believe how different they were.
Thought of another one - I love Gone With The Wind, I've read it several times and will continue to pull it out once a year or so. I've also read the sequel but not as often and the first time I was quite young.... I read it again recently and had to put it down. It wasn't so obvious when I was younger but now I realise how much it is like a sad parody of the original. I like the story, but I can't read it anymore because of the writing.