I've actually never seen anything this bad.

Ok, I'll humor you.
World War Z was an abomination.
The acting, the actors, the direction, the wardrobe, the script, the camera work, the dialog, the story, continuity, suspension of disbelief, the effects and pretty well everything was laughably poor, clumsy, amateurish and a downright failure on every level.

There was not a single thing my Dad(who's an emmy winning producer incidentally) or I thought to be skilled or well done in this film.
Everything right down to the core was worst than some of the feeblest first year film school attempts at film making we've seen over the years.

I've seen better acting in teenage "Live action role playing", actually scratch that. It was on par with a teenage "Live action role playing" because that's what it came off as. A bunch of amateurs overacting and making up the story as they went along whilst being directed by a pimply faced virgin who lives in his mother's basement.
"Oh wow you brought stage blood? Awesome!"
On that note,
I've seen better makeup at our local zombie walk.

Then there's story. Oh god the story was so abysmal I don't even know where to start! The script in it's entirety was so shockingly stupid, trite and just plain embarrassing from the dialog right down to the characters, that I'm not sure where to start save saying that it was just total garbage and had no merit whatsoever. I've read fanfics written by randy pre-teens that were more cohesive, polished, believable and well crafted.
The script was agonizing.

Simply every single element of this "film" was so terrible that words escape me.

We watched the credits roll after and laughed that it so we wouldn't accidentally hire anyone who worked on this film. LOL