You know how the phrase goes: When there are no more comic book summer blockbusters to reboot or ideas to pitch in hell, the zombie apocalypse action movie epic will walk the earth. Or something like that.

So after seemingly countless delays, reshoots and just generally bad news coming from the Hollywood insider magazines, "World War Z" has arrived. And for some odd, miraculous reason, despite all of the off-screen drama, the on-screen drama turned out pretty good. An actual zombie apocalypse breaking out would be less surprising.

Brad Pitt stars as retired UN superman Gerry Lane. He’s driving his adoring family (the fierce-eyed Mireille Enos of AMC’s "The Killing" plays his wife) to school on a traffic-filled morning in Philadelphia when, wouldn’t you have it, a whole mess of zombies storm the morning commute.

After a creepy stay in a ragged apartment complex, Gerry and his family are picked up by a helicopter and taken to America’s last refuge, a fleet of battleships in the middle of the ocean holding military, political and scientific leaders and their families – though only as long as they are "essential."

Gerry is eventually filled in on what’s happening. The zombies have taken over the entire globe. The president is dead. And now, it’s up to Gerry to scour the globe – namely Korea, Jerusalem and Wales – for the virus’s origins and from there, hopefully a cure for the zombie plague.

"Zombie" plague might be somewhat inaccurate. Considering the disastrous production that skyrocketed the budget and the box office demands of a summer blockbuster with franchise ambitions, "World War Z" is saddled with a PG-13, meaning there is little to no actual bite to these zombies. They make a nice mess of the planet, but there was more brain-eating in the zom-rom-com "Warm Bodies."

Director Marc Forster seems to want to give zombie fans the carnage they’re used to. Several scenes feel the strain of the camera wanting to look down at a crowbar lodged in a zombie skull, a severed hand stump or a quick glimpse at some neck-chomping action. Alas, it can’t be done.

It’s best to look at "World War Z" not as a zombie movie (and certainly not as an adaptation of the book, because it’s about as loose as the Umbrella Corporation’s health regulations) and instead as a pandemic action thriller that turns its victims into a screaming mass of running, decaying bodies that may or may not eat people.

As viewed through that lens, "World War Z" works pretty well. There really aren’t enough good virus/epidemic movies out there, so it’s actually really tense to see an outbreak movie with this kind of massive scale and immediacy. Most zombie or epidemic movies have to take a small approach, normally for budgetary reasons, so to see entire cities under attack and the globe at risk is a fairly new and inherently exciting thrill that the mostly exhilarating set piece moments don’t waste.

Plus, there’s the survival aspect of the film that’s always entertaining and fascinating. Part of the reason why zombies are popular right now is because we like to imagine and plan what we’d do in such a situation. It’s interesting to see how people cope with the pandemic, on both a small scale and large.

Jerusalem builds massive walls to keep the zombies out. An early speech from a creepy David Morse notes that the North Korean government mandated the removal of all of its citizens’ teeth after the breakout. Brutal, yes, but Morse also notes that they’re one of the only countries in the clear.

The global reaction is one of the few aspects of the book the script (from a team of Matthew Michael Carnahan, Drew Goddard, Damon Lindelof and J. Michael Straczynski) takes on, much to the film’s benefit.

The human aspect of the story plays well, often times better than the zombie stuff. Most of this is thanks to the performances. Gerry isn't a particularly complex hero, but Pitt gives him all of his star charisma and makes him engaging. When he gets blood in his mouth early on and races toward a tall building's edge, nervously counting down the time it takes to turn, he makes each number carry some emotional weight.

His supporting cast is above average as well, with Enos, Morse, James Badge Dale (previously seen as the main goon in "Iron Man 3") and Peter Capaldi (the viciously profane Malcolm Tucker from "In The Loop") giving their fairly underwritten parts more character than expected. Apparently Matthew Fox is in the movie as well, but he seems to be a victim of the production problems, relegated to a line or two and a credit as a nameless "Parajumper."

The well-documented issues show up in several other places too. The notoriously rewritten and re-shot third act, though suspenseful and well crafted, feels rather small and tidy. Same with the early Korea sequence, which feels unnaturally confined to two sets. The story feels a tad rushed at points as well, especially an early character’s comically quick demise and the ending’s forced attempt at setting up a franchise.

Despite his action movie aspirations, Forster (previously behind "Quantum of Solace") still doesn’t have the best hand for the material. He belongs to the Paul Greengrass school of shaky cam and quick edits but without the same ability to manage and capture the chaos. He's much better when he backs away from the action, holds the camera still and shows the impressive magnitude of the zombie invasion.

It’s hard to say that these issues would be as evident if the production wasn’t such a public disaster. However, hiding how the sausage is made is a part of the movie-making game, and that being the case, there are still some unsavory pig guts and gristle poking out of "World War Z."

Yet despite all the behind the scenes and behind the camera problems, the film works. It’s often creepy, with the set design managing to sneak some horror movie mood – flickering emergency lights and a late zombie-ridden medical center – into the action movie proceedings. There are a few entertainingly jumpy moments, and it’s consistently intense and exciting. It manages to move at a breathless pace while still making time for doses of much-needed humanity. 

In the end, "World War Z" plays much like a zombie horde: a lot stronger and greater than its shuffling, stumbling individual parts. 

For more of Matt's take on "World War Z," click here to listen to his conversation with Brian Kramp on the Kramp Cast.