Any individual is a puzzle, and Richard M. Nixon was no exception, rather living proof. To those who know him and his story (wether through a variety of books or personal experience or even through Oliver Stone's excellent "Nixon") this is a magnificent epilogue that instead of tying all loose threads together, reopens wounds and reformulates old and tired questions.
The film is a mix of fragments of a complex and important life (one that helped shape the modern world) and an equally complex mind. Since only a very long (and impossible, given the obvious budget) running time could grace this with a tight sense of structure, the performance becomes the binding element, which is the key element of this picture. Whether you are interested in history, Nixon himself, character suffering, paranoia, film or acting, this is a must-see, if only for the brilliant performance by Philip Baker Hall. His portrayal of Nixon blows Anthony Hopkins's away in terms of accuracy and is a mighty challenger in terms of acting alone. He may be less sympathetic than Hopkins, but such was one of the real Nixon's flaws (in interviews the real Hall is quite charming!).
Turning a play - especially a one-man-show - into a film is quite a challenge, but Altman, through simple yet effective means (notably the use of security-camera monitors and portraits), cranks up the intimacy and paranoia, ending the film in an uneasy and dark manner that would never be conceivable on stage.
In fewer words, suffice to say that this unusual little film is in truth a giant in movie-making resourcefulness and talent. Unmissable.