Is that your favourite book film that you're afraid to see? Or is it something different?
What about books like Pride and Prejudice? It's a great film, but the book is not too good to read - it's a classic though, so you can't expect too much.
Well... it has been made in to a film, but not in the same way things like The Da Vinci Code, Narnia, Hitchhikers and whatnot have.
Have you seen a film called The Hours? It's based on the Virginia Wolfe book "Mrs. Dalloway", but instead of being the same plot as the book, it shows how the book has affected the lives of three women from different periods. And there are references to the book, and slight snippets of the plot. I imagine that's the same thing they've done with Finding Holden/CitR.