Memento was king for me for a long time but I think Inception topped it. The amount of interesting discussion this film is causing around the country/world and on the Internet is a pretty good indicator that it will be a classic. The ambiguity is amazing and it only holds up because of Nolan's attention to detail throughout the story. He has red herrings for a number of theories as well as plenty of evidence to support a number of theories. It's brilliant, a neverending staircase of an art film disguised as a summer action flick. And I also do not agree with the criticisms of it being unemotional. I was almost in tears during the scenes with Leo and Marion towards the end of the film.