Groovy quote from Liev Schreiber about adapting movies from books, as quoted on imdb.com:
"That's the hard thing about adapting a book that's so well loved. It's like playing Hamlet. The audience doesn't buy it, because they're Hamlet. How could you possibly be Hamlet when Hamlet is them? It's one of those difficult things where a good writer gives the reader ownership of the material. They develop an intimate relationship with it and become its protectors, and rightly so. Whether they like the movie or not, there is something a bit outrageous about exploiting their private story."
I can't improve on that, that's exactly what it's like when a book I love gets made into a movie. It's never quite right because I am not there being the character I identify with most.