Do you remember when Jon Stewart went on Crossfire in 2004 and destroyed the show by pointing out all of its flaws? In a way, that's how I feel about Cabin in the Woods--except without any illusion that the great deconstruction of horror tropes would actually end horror movies. Maybe some writers and directors will re-think some of the silly tropes they've used--the group deciding to split up, the heroine dropping a weapon; but the core of horror is too primal to be let go so easily. Maybe we'll stop picking on teenagers for being transgressive (i.e., being teenagers), but we'll still love the fear of the unknown.
Which brings us to You're Next, which is, in many ways, a throwback. For instance, it opens with a spectacular bit of violence, with some old man and his young sex buddy getting killed by some creeps in animal masks. In classic horror movie form, You're Next gives us some violence against people that we don't particularly care about as our first taste of the danger.
In fact, instead of the cast of genial, smart, funny, and interesting characters in Cabin, You're Next really enjoys making these characters generally hateful, in an almost cartoonish way. It's hard to really take the shallow older brother Drake seriously when he starts talking about how he likes commercials better than TV; and when the young daughter starts crying about how no one ever gives her any credit--when the family is under attack with arrows!--there's really no identification possible with her.
So this movie plays with the audience-as-voyeur, letting us enjoy the comeuppance these characters experience as they make really terrible decisions, often with lots of anticipation and lead-up. For instance, when that daughter gets everyone to agree to let her run for the cars, we get some really dumb ideas--"They'll never expect you to be running all out"--and a slo-mo shot of her running. We know it's going to end poorly; we're even looking forward to it ending poorly; we only don't know what form that poor ending will take.
This even goes for the heroine of the movie, a surprisingly effective survivalist, who is a pretty sympathetic character, insofar as terrible things are happening to her and she has no visible sin to atone for. But her violence is so over-the-top that not even she can justify it: when she kills one person, she answers his "why?" with something like "why not?"
Which subtly changes the tone of the movie, except the word "subtly" has no place in a discussion of this movie. While it looks like a standard horror movie about killers targeting isolated people, You're Next turns out to be more like a campy Grand Guignol laugh-and-blood fest, like a cross between Straw Dogs and Road Runner and Wile E. Coyote cartoons. What's amazing is that, by giving us so little in the characters to care about, the ridiculous deaths can be played for laughs--and it works.