It's a complicated issue for me, this. It'd take a while for me to get my opinions into some sort of argument, but I think that it's important, in order to get the best out of both texts, to concentrate just as much on form than on subject matter. A lot of book-to-film adaptations allow the original text to serve the entire purpose for the second version, so what follows is a story-heavy film. Of course, because films aren't marketable once they're past a certain length, and because adaptations are more often than not financial cash-ins, a lot of adaptations are deemed inadequate because they're not detailed enough, because of time, because of the irrationality of an image compared to a sentence for telling a story. I think a lot of the people in the film industry are under the illusion that an adaptation is like an upgrade - "the Cinema is superior to the Novel", which is of course absurd. On the flip side, of course, you get people who hold a rather snobbish view that film adaptations are somehow ethically or artistically dubious, or wrong. Not so (though a lot result in awful films).

I actually think Fear and Loathing in Las Vegas is a very good adaptation, without having read the novel. Why? Because it makes use of the cinematic uniqueness of the medium. Just like the novel is (from what excerpts I've read) a writer's novel, the adaptation is a filmmaker's film. I don't necessarily like it as a film, but that's not taking away from the fact that it's made the most of the medium's technologies available, and made it its own.

Does The Da Vinci Code do that? Not really. Fear and Loathing is directed by Terry Gilliam, who is more than capable of taking an original text into different and unique realms. The Da Vinci Code is a bit silly, really, in the hands of Ron Howard, a by-the-numbers, conventional filmmaker who, it seems, took the popularity of the book and transformed its structure to form the basis of the film.

Film adaptations which I think are worthy of being made (to name a few): The Godfather, The French Connection, The Magus, The French Lieutenant's Woman. And praising the adaptations is not to say I dislike the originals, or even to say they "needed" adapting.

Forgive my incohesion. Like I said, it's a complicated issue for me.