It appears the movie is nothing like the book. The book, which I highly recommend and I am not even a zombie kind of addict that some are, is a series of short stories. An oral history of the zombie wars. There is no "one" character, superhero like Brad Pitt. There is even one short story from Canadian soldiers in Afghanistan who come upon some Taliban undead in the mountains of Bora Bora. And the zombies are the slow walking dead type, not the I Am Legend superpower type that appears to be in this trailer. In fact the trailer makes it seem quite similar to that movie.
I heard awhile back there was a big fight over the rights to the movie. Looks like Brad Pitt came in and wrote a huge cheque to Max Brooks. He gets to keep the name and that will help sell tickets, but he probably has carte blanche to change the entire story as he sees fit.
World War Z would made an excellent TV series because the stories are all unique and would fit a nice 1hr time slot. Unfortunately with the Walking Dead I doubt there is room for another weekly show on zombies.