Well, everyone seems to be raving about this film, but I can't agree. I went into this film blind - I had seen a mention about it somewhere, but I didn't know anything about the plot. And while the big reveal at the middle of the film is certainly effective, it seems to take a long time to get there, doesn't do much beyond reveal its setup, and then decides to end on an odd note. All of which adds up to a disappointment.
Without giving too much away, the start of the film follows a young man working on a roof repair job somewhere in Europe. He is able to eavesdrop a bit on the conversations in the house, which seem to involve a job for the husband which makes them very uneasy, to say the least. When the husband dies, leaving the worker without pay, he decides to take the husband's place on the mysterious job - he only knows to take a train ticket to Paris and show up at a hotel, nothing more. All of this is done at a fairly slow pace, with lots of obscure conversations as everyone pointedly fails to describe what the actual job is.
The job ends up being a participant in a horrific game set up to entertain some rich Europeans, and the worker is unable to escape until the game is played out - assuming he survives.
As I mentioned above, the reveal of what he is expected to do is horrifying, and the actual execution (so to speak) of the game's first round is suitably tense and draining. However, the same process is repeated a few more times in succession, and since we know the workman will survive (no other competitor is defined as anything more than another body in the game), the tension quickly drains away, leaving us waiting around for the thing to end. And then once it does, we don't really see much about how the worker is affected by what he went through - he starts up a few new plot threads which are not followed up, and then the movie suddenly ends when happenstance brings one of the other competitors back into the picture.
I know this will come across as another "ugly American" opinion, but I can't help but think that an American remake of the film would be an improvement. I don't mean adding more gore, although that would likely happen; I mean improving the pacing, making the thing have more movement about it. And I say this as someone who much prefers most of the original Japanese horror films over their recent American remakes.
I can't give this one star - the brief period where the film gets it right, gets it very right - but it certainly isn't three-star material. Two stars, and let me know when the remake shows up.