It's a lot of fun. I enjoyed it a lot. It's even funny.
Hmm, as an aside, I kinda felt that Anna Kendrick's character was just an extra to add a female into it but she wasn't needed as much as the other lady.
It was pretty good and very emotional. Usually American zombie movies would have a humor relief or something. The dark tunnels gave them too much time and there were parts they could have saved themselves easily but didn't (like the first old lady, she was right near the front). I think the emotional punch just worked with a lot of people.
The big daddy was a bit of a jerk but not as much as the main guy and I was sad to see him go.