The making of the movie is good. The directing OKish and the cast is great and performs well.

However, the story is an anti-climax one. Amenábar builds an atmosphere that promises a lot more than it delivers. In the end, it is just the only logical and down to earth story with unrolls well but it just drives the spectator to boredom.

Good from the philosophical and logical point of view. Bad from the show perspective.