Saw Sin City over the weekend and all I can say is "Wow!" It is incredibly dark and violent (think Reservoir Dogs and Pulp Fiction), but is a technical masterpiece. The acting is phenomenal, no surprise given the cast, but the film-making artistry is unmatched to date.
When you realize that many of the actors never met (at least, on set), even some who fought each other on screen, and that people who didn't know could not tell that the "sets" didn't exist, you can't help but be impressed.