Of my 21 books, three have been adapted to the screen. Midnight Express was an Academy Award winner. Not Without My Daughter was a Sally Field drama. Freefall was a made-for-TV movie starring William Devane. None of these movies was as good as the underlying book (Freefall came closest). And while there a number of reasons for this, the best explanation came from my daughter Jennie when she was six-years-old.
Right from the git-go I had formed the habit of reading to her every evening. In the beginning, of course, these were young children's picture books, with lilting text and bright illustrations. But Jennie was a precocious child and, by the age of six, we decided to kick it up a notch. So, one evening, I began to read The Prince and the Pauper to her.
After finishing chapter one, I set the book aside and said, "Jennie, I'm sorry there aren't any pictures in this book."
She said, "That's okay, Daddy. I make the pictures in my head."
And there you have it. The experience of reading is intensely personal. We make the pictures in our heads. Your pictures are unique to yourself. So if at some future time Hollywood puts the book up on the screen, it forces you to look at its version of the pictures. The result can be dissonance most foul.
This is not to say that you shouldn't try to enjoy the movie version of a book you liked. But you probably won't like it as well as the book.