Oh, novelizations and media-tie in books are an art in and of themselves. It's something I grew interested in after being a kid reading the Star Wars novels which are pretty good to great most of them. Then after the movie Mission Impossible was released I saw the book in the store and got that.
There's an art to it, if you are working from a script like most novelizations then you have to flesh it out and make it work as a book. If it's a media tie in you have to write to the voice of the characters and not destroy the franchise. Like the Monk, CSI, Psych, Doctor Who, etc.
In the case of movies you have to write a book that follows the script but gives enough detail to make it a full reading experience. The highest form of the art is to produce a book that is so good it's as if it is the actual source material. Or in the case of TV tie ins, you can't write a Stargate novel and kill one of the characters when the guy is still on the show. You have to write a new story that knows the characters and world well enough to slot right into the narrative.
I'll also ad that I usually see the movies I read the novels for, after all, I wouldn't have gotten them in the first place if I was not interested in. With big summer blockbusters and superhero movies I know I'm going to see, I like reading them. I get the story in, in detail, more detail event than is usually in the movie even. Where directors and editors sometimes fail at making an important point, or gloss over it too quickly I get the whole picture. Plus, when my buds and I go see a big summer movie we usually go to dinner first, then the bar, then to the movie, by then I'm just there to sit and look at the pretty pictures unfold, not be burdened to try to follow a story though a haze of beers. By the way, Superman Returns, the book ruled, as did Batman Begins, way more detail, Talia even was in there! The Dark Knight was also a great read too.
http://www.iamtw.org/art_licensedfiction.html
http://www.iamtw.org/art_novelization.html
http://www.iamtw.org/art_latimes_08.html
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