Massive fan of the book and went and saw the movie.
I didn't hate it as much as I thought I would. That's the nicest thing I can say about it. There were, grudgingly a few sections of decent action and even a few freaky moments and even one or two actual emotional scenes that suprised me. Also there are a few, a few and incredibly sparse moments clearly taken from the book. There is a bit from Korea where we see an old doctor tending to a patient (in the book it was China and he didn't get eaten but whatever) which reminded a lot of the first chapter of the book, there was also an extended bit in Israel talking about ho the country sealed itself up and let refugees in which was another section from the book (there was also a spy-type character who mentions 'digging' for information which also happened in the book) and once or twice the term 'Patient Zero' is dropped also I'm not sure but a possible reference to the nuclear attack between India and Pakistan might have come up.
But that's about it. No mention of Jessica Hendricks and her family traveling up North, no mention of Yonkers or Todd Wainio, no Paul Redecker, no pilot who possibly had split personality disorder. Also Israel gets attacked which never happened in the book but it was still one of the best action scenes in the movie so maybe that can be forgiven and for a movie called 'World War Z' we see America, Korea at Night, Israel and somewhere in Glascow. Other places we just see in Montage form.
Plus I'm not going to spoil it but there is a huge 'fuck you' deus ex machina ending that really doesn't belong anywhere near Max Brook's story. Maybe if it had just been Brad Pitt's character going all over the world with each section being a reference to some event that happens in the book like Yonkers, the mass immigration of India, The travel up North and The South African plan maybe then the movie wouldn't be quite so painful. It still would only vaguely resemble the original movie but there would still be some fun in a 'hey look remember this from the book?' kind of way.
Also, PG-13. This is easily the most tame zombie movie I have ever seen. I don't even remember seeing a single drop of blood anywhere in this movie. It's a zombie movie gore is kind of expected. And the Max Brooks zombies were flesh eaters, people getting infected were incidental whereas in the movie a point is made that the zombies are only trying to infect people.
Ehhh I'm mad at this movie but there were a few genuienly okay elements that softened the blow. There are worse things to watch and in terms of bad adaptation it at least isn't Cat in the hat levels of bastardization. However the much better zombie movie of 2013 is still The Evil Dead so if you must see two zombie movies this year, watch that one first.