Why not both?
I have always maintained -- since I saw the first of PJ's films -- that a real effort was put into them by some very talented people who did actually read the book, and that the spirit of Tolkien's middle-earth was not wholly lost in the translation -- some few bits were even better than my limited imagination was able to get from the book.
I am a musician by trade. I love to hear great interpretations of the music of those no longer with us. Although translating a book to film is not exactly analogous to interpreting an old manuscript of music (for one, the musician is expected to perform the written music, while Tolkien probably never expected his words to be 'performed' on film), there are some similarities. E.g., as a trained musician, I can take a score for, say, a Brahms symphony, and enjoy it even without physically hearing it. But I know most people cannot do this. I rejoice over good interpretations -- not only that I may physically hear them, but that those who can't read a score very well can also enjoy them. Even when the good interpretation is lacking in some areas.... as it always is with a genius like Brahms. But the good interpretation often shows me things I never would have seen the the score on my own.
I rejoice over the movies for the same reason -- not because they are an exact, perfect interpretation of the books -- but because they are a good one -- as good as can be got at the moment -- and they not only allow me to physically see and hear a good interpretation of the story, they allow those who can't or won't enjoy a long storybook to enjoy the story.
Besides, if you watch even a fraction of the 'making of the film' extras on those DVDs (yes, I own them all), you soon come to an appreciation of how much sincere effort went into making each culture, each place, each costume, each accent, each character, each special effect, each bit of music, etc.... Despite what you'd think from reading most of the posts lamenting the fact that the movies missed this or added that or were inaccurate here or changed the whole spirit of a character there -- I believe a large number of the writers, editors, actors, and others involved in the films did consult the book -- extensively.
Now don't get me wrong -- I still abhor the movie Faramir's character change, among other things! -- and if I had PJ's resources and the inclination, my movie version would be different --
So the books are essential.
The Council believes Elanorraine beautifully explained what the movies mean to her and made a very astute link with music, and therefore Elanorraine will be awarded with Post of the Whenever.