The fear factor about low budget films like PA is that they don't rely on the obvious, psychotic, knife wielding vampire madman to get you going. PA relies on the purely instinctual human habit of connecting with a seemingly 'normal, young couple' and the almost believable way we come to know the events as a haunting, and they come to experience as the horror of their lives. The director heavily relies on our eyes' tendency to 'i think i saw something but i can't be sure' stint. And what really makes the movie is that, between skeptic and believer, who knows what actually happens when we're at our most vulnerable, when we're sleeping at night? Go see it with an open mind, and you'll lose a few hours of sleep.