If you like zombie's gener you will love this movie ... or not!
It cheats in a cheap way through creating 2 level of zombies: the good ones and the bad ones. Also, it breaks tons of zombies stereotypes to be able to build the story, that's why you may end hating it if you are a "purist".
As this is not my case, I really enjoyed this movie. Fun script, good casting and great performances by Hoult and Palmer. Also, always a pleasure to watch a movie with John Malkovich.