Mostly pretty spoiler-free until the end:
I'm not going to pretend for even one second that I went to see Cabin in the Woods with any sort of objectivity. A story co-written and produced by Joss Whedon? The other co-writer is Drew Goddard who was responsible for a great deal of Buffy/Angel? Yeah, no, I'm in and I wouldn't have cared if it'd been about a sentient q-tip having an existential crisis. What I'm saying is: I went in with the expectation of enjoying Cabin in the Woods and I did. Immensely.
This admission of my bias is so, when I say it was brilliant, I'm not being dishonest about my predisposition to give it every benefit of the doubt and possible pass. I could, I suppose, but the film doesn't need them. It stands on its own as a transcendent piece, a perfect blend of insightful, sharp, critical horror and exceedingly clever humor. Since scaring people (or, more accurately, horrifying them) is pretty difficult, combining that with the even more difficult challenge of making them laugh...this movie managed to give me the giggles AND the creeps...while also compelling me to think deep thoughts about storytelling, culture, and what the point of humanity really is as we continue to tell each other tales. It's absolutely a story about stories and the resonance they have in our lives. The "power of myth", if you want to be a little pretentious. And I do.
You see, movies like Cabin in the Woods, ones that clearly love storytelling to such a deep degree that they will simultaneously exalt it and poke fun at it, basically give me a warm fuzzy feeling not unlike the way a really happy cat will purr when you scratch their chin. Stories that revel in the absurdity and terror of horror as a genre...not to mention the ability of said stories to make you feel something so profound you're laughing, crapping your pants, or crying...make me happy on a level usually reserved for dark chocolate gelato and cuddling.
SPOILERS! (and with this movie saying nearly ANYTHING about it is a spoiler)
It's a fantastically crafted story, with one of (if not the) most satisfying 3rd act monster reveals of all time (you might even be able to argue it was a 4 act story, but right now I don't care about that kind of detail). Even that might be too much information if you haven't seen it. If you have, you KNOW what I'm talking about and are likely grinning like hell right now. It's that good, especially if you're a "true" horror fan and can spot the tropes being played with.
Cabin in the Woods is about as satisfying an experience as its possible to have, and I'm just beyond thrilled it was made and came out. Intelligent, funny, smart movies are hard to come by. I wish that wasn't the case, but, at least we got this one. It'll make up for a lot.