I don't read a lot anymore so many of the films mentioned I've not read the book. I have read Northern Lights and agree that the ending was "Noooo, you can't do that!!!!", which was brilliant. I think it must be very, very difficult to film a book as (not including any particular studio's ethos and the need to recoup huge amouns of money) one person (or small group of people) is putting their own imagination, as inspired by the book into 'reality'. When I read a book I get a whole reality open up in my mind, including smells and touch - which cannot be replicated in a film, so it's unlikely any book can be recreated 'faithfully' and meet my own imagination.
Even 2001, in which the book and film were developed together, had it's limits. the book 'The lost worlds of 2001', if I remember right, had numerous scenes in it that were unfilmable at the time and so did not make either of the official film or book - so 2001 did not even meet the authors imagination and he was in on both....
However, Hollywood remakes and shit versions etc can really suck