Yeah, a lot of people don't seem to "get" the film. It's not supposed to be a serious horror movie. It's not supposed to be filled with stellar acting. It's Joss Whedon both poking fun at, and paying homage to, horror films in his own unique way. The juxtaposition of the humor/horror was typical Whedon for anyone who's seen his work. Someone I know who is otherwise hip and smart and not your typical person said, "I didn't like it, it wasn't scary enough."
