This film relies on the final 20 minutes to make it different from the other films that have come out in recent years. The twist surprising to me would have been pretty mundane if I had watched that trailer prior to seeing the film. Maybe not totally as there are a couple very significant revelations. It shows there is a real line between building a trailer to sell a film and building a trailer that can ruin a film by giving too much away. I would suggest NOT viewing the trailer prior to watching this film. The twist is subtle but cutting and changed the film in my mind from ho-hum to passable. No explanation here since I would say wait until you can rent this one on the cheap but do check it out.
Rating (5.5) 5.0 and up are recommended In the Zombiegrrlz system I say Rent it!