I went with friends and liked the movie more than I expected to (I probably wouldn't have seen it on my own). I thought the zombies looked frankly ridiculous when they were running and jumping and flailing their arms about en mass. They worked a lot better in the second half of the movie when Brad & co. had to sneak past them in dimly lit hallways.
Early on I had bad flashbacks to Spielberg's "War of the Worlds". I'm glad this film had the sense to leave the kids behind after the first 20 minutes or so.