A well thought out movie.
Yes it's not really focused on the zombies but it indeed uses every bit of their screen time to be terrifying as hell. I can feel the tension everytime they showed up since you can never tell when they'd pop up. IT'S A PSYCHOLOGICAL HORROR taking place in a zombie apocalypse. If you're a hardcore zombie fan then you should go watch zombieland. This movie focuses more on the story and its characters, not really killing and slaying zombies like in left 4 dead. The GORE is DAMN GOOD.
I would recommend watching this for the sake of the story and it's cinematography. It's pretty unique after all.