I won’t debate whether it is generally considered trash. I think it is a great book and Puzo was a fine writer. The beauty of this combination for me is that Puzo wrote the book and the screenplay and thus the film is very faithful to the book. The fact that I am not entirely pleased with the third movie in the series is compensated by the fact that, at least it happened as Puzo intended.
Invasion of the Body Snatchers was written by Jack Finney.
delphica, count me in also amongst the person who loved the animated Watership Downs. Although the mythical rabbits parts reminded me more of Australian aboriginal art than 70’s art.
Another interesting one is Who Killed/Framed Roger Rabbit. Both are good and both take into account their medium of origin, i.e. the book concentrates on comics characters, while the movie concentrates on cartoons.