I will say this now, I have had a terrible man crush on Brad Pitt for like a long time now. I can't help it... It's that dern smirk!
That out of the way, WWZ as a film was fun, light, and rather silly. The waves of zombies were actually quite funny. In a completely ridiculous scenario, the solution was actually kind of intelligent. I like that the movie took parts directly out of the book, which was also fun, silly, and light. Zombies as undead walkers are a fantasy.
The reality of a true zombie outbreak is going to look a lot more like a scarcity event, like water or food. I'm re-reading WWZ, and I just read the part about the celebrity house, and I see that as a much more analogous event. Like, we're all starving, and there's our celebs hiding in a fortress while the rest of the world crumbles, and posing a live web feed of them partying. Yeah, lets tear those walls down!
When something we really need becomes scarce, then we'll see a "zombie" apocalypse in the form of the sick, hungry, and homeless. It would actually be a lot worse than if everyone was a mindless zombie. Instead they will be good people, turned desperate, giving into their darkest desires as they try to get some fulfillment from the last moments of their lives.
Another interesting read in this vein is "One Second After" which was written by a buddy of Newt Gingrich. It details how the community of Black Mountain, NC and Montreat College survive after EMPs are detonated above the US, disabling all microchips and electrical systems. That's a more likely Zombie Event.