It's Brad Pitt vs. the Zombies in what looks to be the biggest budget zombie movie of all times. While it shares the same name as the best-selling Max Brooks' World War Z: An Oral History of the Zombie Wars, there's not supposed to be much else in common between the two.
The departure from the source material, plus reports of substantial re-shoots to fix serious problems with the original draft of the film have many dumping on this film already. The zombies this time around look to be of the "fast" variety, and the trailer shows that the Zeds are at least capable of enough thinking to come up with a zombie pile/ladder to overcome obstacles.
Why you'd make a movie based on a book, and then not base it at all on the source material, is beyond me. But, it's a big budget zombie extravaganza, so I'm pretty much in regardless.