A very silly movie, this starts with a soft porn sequence, ventures into farcelike comedy in the art gallery, adds a shocker of a discovery in the hotel room then introduces a random murder for no obvious reason.
What follows is bizarre and surreal (the stopwatch scene in particular is exquisitely unnecessary), culminating in a revelatory "twist" ending which is as obvious as it is unfair on the viewer (see the trivia section for precisely why it's deliberately unfair).
The movie goes out of its way to be offensive to as many groups as possible - transsexuals, the insane, and the wonderful "Huggie Bear"-style racial stereotyping on the subway - and condescendingly treats the viewer like an idiot in the closing scenes, as characters endlessly explain to one another in great detail and over and over again what just happened in the film. Though the background female characters in the restaurant scene at the end are a joy to watch.
In fact, the whole movie is a joy to watch: Despite its many, many flaws, the whole package just, well, works.