One thing I've come to expect from Joss Whedon is his impeccable timing in dialogue. I was not disappointed. I am a jumper. This means that when I attend a scary movie, I jump, and I jump high. There are definitely the jumping aspects to this movie. At one point, I had just taken a drink of water and wasn't expecting the jump. I jumped really high and spilled my water all over myself. That being said, I think I laughed way more than I jumped. The writing was awesome. It's like he took all those little satirical jabs he could, but he was totally inoffensive about it. I was more than pleased with the writing. Now that I think about it, this movie kinda reminded me of that episode of "Supernatural": "Babylon Hollywood".
I'm not going to give away anything in the story in this post, but I am going to say this: The ending was just terrible. Once the credits hit, all I could do was sit there and wonder if that was it. I even waited for a clip after the credits that didn't come. I was so horribly disappointed with this ending. In fact, I have a better ending all thought up.
If you want to know my better ending, you will have to check out my "Cabin in the Woods" Spoiler page. It is password protected, so you have to be pretty serious about wanting to know how it ends. The password is citws (cabin in the woods spoiler).
All in all, I would have to give this movie... 3.5 stars. The writing was good, and I love Fran Kranz, but the ending just totally ruined it for me.