The Assassination of Richard Nixon (2004)

Received information has it that Sean Penn is the greatest actor of his generation.  What does that mean and where does his generation start and finish?  I'm not sure that I agree (if in fact the terms were spelled out), but his roles often turn into a master-class of angst.  However for a film to move me, I need to find some level of identification which is so often lacking in Penn's showy roles.  Here he brilliantly portrays a complete loser, estranged from his wife (a hard to recognize dark-haired Naomi Watts) and family, unsuccessful at his current job, frustrated by the obstacles in trying to start his own business, and generally ready to blame the rest of the world for his failures.  Purportedly based on a true story, he confides his frustrations in tapes which he mails to Leonard Bernstein and decides that killing President Nixon by hijacking an airplane and having it crash into the White House (the film is set way before 9/11) will make the world a better place.  Needless to say his plan, like the rest of his life, was doomed to fail.  Mr. Penn keeps threatening to retire from films; I wonder what would happen if he lightened up.