eh, it was OK.

Rating: 6/10 (14 April 2012)

Spoilers below:
I went into this movie with very few expectations. I had not seen the trailer and I had only heard about it when I decided to go to the movies and checked what was playing. Seeing the high rating at IMDb and rotten tomatoes I decided to give it a shot. I am not a huge fan of horror movies, but I do enjoy things which are creepy/psychological. I avoid movies if I think there is a lot of gore, and at the beginning of this movie I was a bit worried about the gore factor, but there is, in fact, very little gore. Someone said it should be 17+ but I am not sure why. The "Nightmare on Elmstreet" movies are way more disturbing and I saw them when I was a kid. Yeah, there are some boobs in this movie...big deal. Otherwise I think it's OK for teens who like horror movies.
I cannot for the life of me understand people who said the ending was a big shocker. As soon as blood was poured through that outline of a figure it was obvious to me what was going on. That was pretty early in the movie. I found the ending to be a bit of a let down, as there was nothing really surprising or mystical. In fact I thought it was just cheesy. (Spoiler!) When Richard Jenkins' character said "kill him" I really hoped there'd be someone around the corner who could be killed, someone who was controlling everything. So...what was really there just seemed dumb. And we never found out who was "upstairs," that would be interesting. The last two characters' attitude towards everything at the end was also pretty comical. Maybe that was the intention - this movie kind of shows people's weakness and unwillingness to sacrifice, instead of the willingness to sacrifice which is shown in war movies.
This is more of a bloody comedy than anything. It might be similar to "Zombieland." I guess it is also like "Cloverfield" as some people have already said. Some of the details were amusing - the room with all of the objects, each connected with a horror character, was neat, and seeing them all together in different boxes was also impressive. I also found that invisible grid (and (spoiler!) the scene with the main "athlete" character, when he tried to jump to the other side of that canyon or whatever you'd like to call it) to be interesting. The rest of it was so-so.
I would say it is a watchable movie and somewhat new in its approach, but it is not really a horror movie. Thriller, yes, but not horror and not really psychological either. It is kind of funny to see this movie come out at the same time as "The Hunger Games," because it seems like there's something similar between the two.