Ok, I saw the movie some hours ago - lots of girls and couples in the cinema (the Brad Pitt effect). I kinda liked it, but still can't understand why it's called World War Z. It doesn't have anything to do with the book! And that what's wrong with it - everyone who sees it and knows the book, will draw comparisons and when doing that, the movie fells short.
Forget all about the personal stories you see in the book - here you just get to see Brad Pitt running around the world, trying to find a "cure". There's some rather good actions pieces (I really liked the initial outbreak scene; the running battle on Israel and the passenger's attempt to defend the airplane) but not enough action.
Most of the infection happens off-screen and that kills it for me. I really hope they do some sequels and we get to see what happened around the world. They could follow some other paths of the story seen in this movie: the lives of the soldiers on Korea (before, during and after the infection); the missions of Matthew Fox's character (I gather his mission was collecting survivors from the cities); the story behind the nuclear explosion they see from the air, etc...
Final verdict - a good zombie movie for the family (there's no gore, just some scary/jumpy moments) that shouldn't be called "World War Z".