I've thought about this movie for 8 years and finally decided to comment tonight. It still is disturbing to look back on. I clearly remember the outstanding cinematography and artistic direction. I saw it in the film festival - watching was not pleasurable (I can see suffering from bad dreams after viewing it) - but you have to admire the creativity and execution. I've never seen a film's mood have such a profound impact on friends.
In fact, the mounting tension (mostly thru pacing, lack of dialog, and the way you'll start to feel like YOU, the audience, are in a mental institution) drove my friend to flee the theater. Really. He ran out because he "just couldn't take it any more".
I bet at least 1/2 the people in the world would walk out - either because they are bored, confused, or disturbed by the film. But if you set out realizing you'll need to invest your attention, emotion, and patience, you'll be rewarded with an unforgettable film. And it is great for discussion with friends afterward.
