I'll start with the simplest sentiment: go see this. See it now. Don't spoil yourself or read too much about it. Just go see it and trust that you'll have a terrific time at the movies.
Now, to address a few things I've seen on twitter or in comment sections:
"I don't like horror. Will I like this?"
I'm not what you call a horror fan. I do enjoy a few of the classics (The Exorcist, The Shining, Carrie, Alien, etc.), and have watched many of the 80s and 90s kill-the-teens slasher flicks (which, if you've seen, will make you appreciate just how much Cabin plays with genre tropes), but I don't go out of my way to see horror movies, and would put them toward the bottom of the genres that I enjoy. Given that, I enjoyed the hell out of Cabin, and would recommend it to horror lovers and horror neophytes without reservations.
"I don't like gore and blood and scares."
At the end of the day, this is much a spin on the genre as it is a "pure" horror movie, but it does have scares and character deaths. Judge your tolerance for such like this: it has as many "scares" as does a top flight episode of Supernatural, and as much (or less) blood and gore as an episode of Game of Thrones. This stuff is there, of course, but Cabin is in no way equal to things like Hostel or the Saw franchise.
"Well, if it's not shit-your-pants scary, then why is it a horror movie?"
I can't answer this without going into spoilers, but it plays with the conventions and tropes of horror as skillfully as any movie I've ever seen. Think along the lines of Shawn of the Dead or the Evil Dead movies.There have been a lot of comparisons to Scream, and while you could make parallels, the teen characters themselves don't consciously comment on the self-awareness of the typical horror movie conventions. Rather, the narrative and presentation of the movie itself does, though there is a (spoilery) explanation for why these tropes exist -- all over the world -- in the first place. HOWEVER, you WILL see many of the things you, as a viewer, have come to expect in a horror movie. Dark, forbidding places. Exploration and confusion filled with tension and dread. Supernatural creatures and acts of violence.
- It's FUNNY. I mean, laugh out loud funny. Yes, of course, the script is filled with your trademark Whedon wit, but there's also the comedy of recognition. Not just recognizing the average horror movie plot elements and tropes that are being paraded before you (though there are those in spades), but also the recognition that comes from watching the layers of the movie get peeled back, and peeled back and peeled back again until you honestly guffaw audibly in the theatre at the sheer scope and audacity of the thing. The casting is uniformly excellent (and Whedon fans will smile at the familiar faces), but Richard Jenkins and Bradley Whitford own this movie. Every moment they are on the screen is pure gold.
- The other thing that makes me adore this movie is what's going on underneath (and I don't mean that in only the literal sense). It has some amusing -- and thought-provoking -- things to say about free will, our increasingly voyeuristic society, and our complicity in the horrors of our entertainment. I won't say more than that to keep this spoiler-free, but I can guarantee there will be scholarly analysis of what this movie is putting down for years to come. But that makes it sound stodgy. Did I mention that it's just FUCKING FUNNY?
Bottom line: Go see Cabin in the Woods. Like, now.