Sometimes you don't need frantic action or buckets of blood to have a movie that scares you out of your seat.
Like the character in I am Legend, there are few people left on Earth at the end of this movie. Tokyo is a ghost town. Where did they all go? That is left for you to argue. Good film for a discussion group.
Is there a finite space where all the souls of the departed go? What happens when that space fills? Interesting questions that are addressed in a very creepy manner by this movie.
But isn't the universe expanding? Do we have to worry now. Is death preferable to living, if you are lonely? You are constantly thinking while you experience this film, and you are never sure of the answers. Call it "adult horror," if you will. It is definitely one to see.