Gonna give this a 2 because there were some interesting ideas. It's just a shame almost all of them either led to nowhere or were contradicted later in the movie. There powers don't come from killing the children, then why kill them? Something about consuming their weakness? Seems like fire and getting hit by sticks was her weakness to.
Also why did no one question the zombie? Maybe it's just a normal thing in that world? People get attacked by zombies every now and then. No idea, because it never bothered to establish that. It's not a deep plot when the viewer has to bend over backwards to explain away plot holes, it's just lazy writting.