This review is absolutely spoiler free—which took some doing, lemme tell ya.
I expect this to be the shortest review I ever write, since almost anything I could tell you about The Cabin in the Woods would risk robbing you of some of its considerable pleasures. You can read this review in total safety (I promise), but don't read other reviews. Don't even watch the trailer. Just see the movie. It isn't perfect, and it probably isn't for everyone, but it's smart and witty and a hell of a lot of fun.
Here are seven things I can say about it, without ruining anything:
1. The Cabin in the Woods stars Chris Hemsworth, Kristen Connolly, Anna Hutchinson, Jesse Williams, and Fran Kranz as typical college students who go to a typical cabin in the woods and find themselves embroiled in a typical horror movie scenario. It also stars Bradley Whitford, Richard Jenkins, and Amy Acker, as other people.
2. The Cabin in the Woods is a horror movie. It is also a postmodern satire on horror movies that breaks down the component parts of the genre and reassembles them to say a great many things about storytelling, religion, voyeurism, the consumption of popular culture, and why we love these kinds of movies in the first place. It is co-written and produced by Joss Whedon (Buffy the Vampire Slayer, The Avengers), who is, for my money, the master of doing several things at once in this way.
3. The Cabin in the Woods is way, way more fun than that description makes it sound: if you like films like Evil Dead, Shaun of the Dead, and Slither, you're probably going to like this, even if you couldn't give a crap about all that postmodern, metafictional claptrap. It has considerable (though mostly comic) gore, a couple of naked boobies, and a script that manages to be funny, scary, and wildly original.
4. The Cabin in the Woods is co-written by Drew Goddard (Cloverfield, Lost, Buffy), who also makes his directorial debut. If I have one criticism of the film, it would be that Goddard's direction is capable, but not yet at the level of the screenplay: horror is a genre that requires very precise filmmaking, and the filmmaking here is a little rough around the edges. That gives the film a campy charm, but it also means there are moments when action sequences don't quite flow together perfectly, and the film is never quite as scary as it should be.
5. Of the cast, veterans Whitford and Jenkins are very funny, handling the screenplay's trademark Wheodonisms with wit and aplomb. The breakout star, however, is Fran Kranz (who may be unfamiliar to those who did not watch Whedon's short-lived sci-fi series Dollhouse). One of the requirements of a Joss Whedon script is the ability to pivot from broad comedy to poignant emotion within the space of a single sentence, and at this Kranz excels. He deserves to be a star, and if enough people see The Cabin in the Woods, he will be.
6. All the talk about spoilers and avoiding spoilers (including mine) shouldn't give you the wrong impression. The Cabin in the Woods isn't one of those movies that tries to fool you by making you think one thing is happening and then turning everything upside down in the third act with a stupid, unwarranted twist. (I hate those as much as you do.) In fact, we are introduced to the twist before we are introduced to what is being twisted, though we don't learn exactly what it all means until later. The Cabin in the Woods is a movie that is continually surprising—in constantly shifting ways that turn out to make total sense—rather than a movie that contains one major surprise for shock value.
7. The Cabin in the Woods is slightly unpolished, fairly inexpensive-looking, and deeply, gloriously silly. But it also has genuine stakes, actual horror, and more on its mind than a dozen larger films. Whedon and Goddard are now Hollywood bigshots—Whedon's The Avengers will undoubtedly take over the world next month—but it's to their credit that they are still in sufficient touch with their plucky, nerdy roots to make The Cabin in the Woods: a low-budget, high-concept cult film that recalls the cheesy teenage horror films of the past while simultaneously guaranteeing that you will never, ever think of them the same way again.