The hook of Max Brooks' "World War Z" was that it told a mostly conventional zombie movie story (zombies happen, things go bad) in the style of a historical narrative. Judging by it's trailer, "World War Z: The Movie" - which is already almost-garaunteed to be a huge pile of shit, BTW (seriously, your movie is so bad that a Damon Lindelof ending is going to HELP!? - has opted to just be a mostly conventional zombie movie. Brad Pitt stars, because other actors were starting to get jealous of him having been in nothing but really good movies for the last half-decade or so and Brad Pitt is humble like that:
So... doesn't look TOO bad, but also doesn't look deserving of Brooks' awesomely exploitationish title. If you're not going to film the book, then a title like "World War Z" where the Z is for Zombies should be selling something that looks like "Starship Troopers" crossed with "Planet Terror;" whereas this just looks like the flashback parts of "I Am Legend" with less interesting cinematography.
BUT, I'll give it this: Zombies are reliable enough that if you can't think of anything new to do with them narratively something new visually can still be "good enough;" and in this case swapping their default behavior patterns from "feral humans" to "fire ants" looks like it could maybe do the trick - the "zombie wave" is a money shot if I ever saw one, regardless of how the rest of the thing is.
I don't think I'll ever be "okay" with fast zombies, if only because it just doesn't "work" with that whole "walking dead-person" thing that's supposed to be the whole point of this particular monster. When "28 Days Later" invented this schtick, part of the new angle it took was that it was "zombie horror" but with creatures that weren't zombies - they ("The Infected") were something else. I feel like we should've stuck with that, instead of conflating the new "Infected" monster with the then-resurgent zombie meme.
Maybe that's still the best move: Someone should come up with an entirely new classification for "Fast Zombies." It would actually make more sense, since the whole point of Zombies as monsters was to play on fear of death and the fast ones aren't really doing that - especially not in THIS. I like the wave/ants motif partly because it's the next logical extension of what Fast Zombies represent - no fear of death, but fear (and, let's get real, hatred) of other humans. A big, writhing, mindless, vicious horde of humanity (but "de-humanized" so it's okay to enjoy mowing them down, importantly) bulldozing over and through everything in it's path? That's not about death anxiety, that's about... well, take your pick: Overpopulation? Urban sprawl? Crowd panic? General disconnect from "everyone else" in our increasingly self-centric modern lives?