This movie is set 4 months after the outbreak of a zombie creating pandemic across England (maybe farther reaching, but its hard to determine based on the two movies). The U.S. military has stepped in and his helped to rebuild a community in London. People are checked for infection prior to being allowed in and then remain to repopulate. However, just as you'd expect, someone gets through, makes one dude get infected, and then BAM! plague all over again!
This movie had some really good action/gory blood zombie eating scenes which for me made the movie much better than the previous movie. In one shot that I thought was really cool, there is a man driving a helicopter attempting to pick up the few non-infected people running for their lives, and to stave them off while the others run, he uses the helicopter blades to chop up the zombies as they continuously run into it. Awesome scene!
As for movie quality, its not the greatest. But its certainly better than 28 Weeks Later. If you're into zombie flicks or gory movies, then its work checking out, otherwise I wouldn't bother. I watched both this and 28 Weeks Later upon the recommendation of my co-workers. I'd say that unless you're in a similar situation, just stay away.