I've seen some movie ratings that place Memento as the best movie of 2000. That's a stretch, but I'm willing to recognize that this was a very different approach to story telling with an overall premise that keeps the viewer closely tuned in throughout.
Guy Pearce plays Leonard, a man who has completely lost his ability to remember anything after the rape and murder of his wife. Piece by piece he is determined to find who killed her. To do so he has to develop a system of note taking on Polaroids to replace his short term memory.
Take these assumptions and then tell the story backwards and you can see why this movie challenges the viewer. At the same time it was never obvious how everything was going to come together.
I give high marks to director/screenwriter Christopher Nolan for pulling off such a twisting and jaded thriller.
My favorite sceen was when Natalie (Carrie-Anne Moss) is telling Leonard what a loser he is, swearing at him and calling him names while walking around the room picking up all the pens. She leaves the house and Leonard is desperately trying to write himself a note not to trust her but can't find a pen. Shortly afterward Natalie walks back in and is as sweet as can be knowing he doesn't remember any of her previous lashings.