Summarize the following movie reviews:

1. A very clever, complex and extremely well constructed movie which demands intelligence and constant attention from its viewers, yet is put together using only a handful of simple elements.
2. Walking out of Memento, we can be glad that we don't share Leonard's amnesiac condition; it's the kind of film you don't want to forget.
3. It's absolutely brilliant--a terrific little thriller that takes the genre and turns it inside out.
4. MEMENTO is not just a movie, but a puzzle.
5. Although gimmicky at times, Memento takes an innovative approach at storytelling that yields a surprising amount of mystery and suspense.
6. A con in the mode of Bryan Singer's The Usual Suspects--the scam of the year.
7. A film that simply gets so much right that there doesn't seem to be anything of real worth left to say about it once you see it.
8. A joyously twisted Rubik's Cube of a movie. One of the year's best films.
9. Christopher Nolan's extraordinary film is a brainteaser and a heartbreaker.
10. Films so seldom take chances anymore, it's refreshing to see one that at least tries for something different.

Summary:
Christopher Nolan skillfully guides the audience through Memento's fractured narrative, seeping his film in existential dread.