Movies and books are often times two sides of the same coin, but recently they seem to have diverged to the point of being unrecognizable. If I can read a book and watch a movie, both with different titles, and only vaguely feel like they are connected by some subject matter coincidence, then they should not be considered the alternative media representations. Had World War Z the movie had another name, I would not have known about the book, but luckily watching the movie did not spoil World War Z at all as they share only a name.
World War Z is one of the best books I've read in a while. Seriously, it is a very interesting analysis of humanity when faced with the threat of extinction at the hands of the undead. This book is a thinly veiled piece of political and social commentary. While you might disagree with how realistic certain situations might be, or disagree with what is implied about humanity, the book nonetheless is quite interesting and enjoyable.
On the other hand, World War Z the movie shares two things with the book: the title and zombies. Almost nothing else survives. Part of the bit about Israel overlaps but that is basically it. I found the movie to be entertaining, but I am very glad I saw it before reading the book. This is because of The Count of Monte Cristo. One of my favorite books of all time, so when I found out there was a modern movie I was pretty excited; that is, until I saw it. The movie and books again shared a title, the names of a few characters, and a handful of slight similarities. But I found that movie to just be horrible because of the expectations set by the book. World War Z made into a movie true to the book could have been awesome, just like The Count of Monte Cristo could be an awesome (albeit likely 12 hours long) movie.
I don't understand what goes through the minds of movie producers. Scratch that, I understand it, but I disagree with it. My understanding is that they are trying to appeal to the broadest audience, spend the least amount of money, and make something passable enough that it sells a lot of tickets. Okay, as a for profit enterprise I guess that is reasonable. However, it robs us of great, entertaining works of art. There is an implicit assumption about the level of intelligence and attention span of the average moviegoer that goes into the decision to make a more action oriented film version of a book. Even though this is true, the fact remains troubling.
My recommendation is to see the movie, and then read the book, or just read the book. I found the book to be thoroughly readable and entertaining, and yet still "deep" in some ways. If you really concentrate on the reality of what a zombie plague could do to the world, and then tie that back to an allegory about the current state of the world, you are left with something meaningful to think about.