I've read the book. The movie's probably a good step in for people who are interested in the overall plot of the book but the movie script probably did without a good portion of the language incorporated into the novel, which is a shame. But, like any film adaptation, it's exciting to see the directors' visions of how the plots and characters pan out.
Basic info about the movie/book: six interlocking short stories taking place in different chronological time periods separated by ~50+ years feature characters that are just barely connected to each other affect each others' lives somehow, because it's implied that they're reincarnations of the same soul. The story is basically an exploration of a soul's possible outcomes as they are manifested in people, with each main character vastly different from the last. The book uses different mediums for each character's story--epistolary, interrogation, journal, novel, just to name a few. I'd surmise that the movie will try to emulate that to the best of its ability. Hope that cleared some confusion up from the trailer.
