I'm late to the party with this one, but I can't fathom how anyone would rate this movie lower than a five star review. It's kind of difficult to believe actually. The only reason you can compare this to Wolrd War Z is because the zombies are almost exact in terms of how they move, and yes there are several shots of the zombies piling up, but that is literally the only comparison. Ignore the "it's just like World War Z but on a bus" because that is false. Plus every zombie film has been done guys, there's no way to really do something that hasn't already been done with this genre. Unlike most zombie flicks, this one had so much heart and a wide range of interesting characters to follow, love or hate. It's intense, thrilling, and extremely heartbreaking. Yeah, there's a few moments of incredibly cheesy dialogue and bad acting, which is almost always expected, but overall all the good overshaddows those tiny instances, and I must note that this was an unpredictable film, something that stood out to me.
Bottom line, watch it. Worth every penny and every minute. As soon as I finish this review I will be purchasing the movie.