The two movies that come to mind when I think about Sean Penn and his acting ability are not Mystic River and Fast Times at Ridgemont High. They are Carlito's Way and Sweet & Lowdown. In both of these movies, he immerses himself in the characters, while in most of his other movies, including the art house hits like 21 Grams and Hurly Burly, he plays more or less the same type of person. Sweet and Lowdown has Penn playing a self-absorbed classical guitarist who obsesses over a world-renowned guitarist much in the way Woody Allen obsesses over things in his other movies. Woody himself shows up as a commentator (this, like Zelig, is presented in mock documentary fashion). It is amusing, if slight (and a sign of things to come in 2000-2002, with Small Time Crooks, Curse of the Jade Scorpion and Hollywood Ending). Samantha Morton won a justified Oscar nomination, but Uma Thurman and Gretchen Mol are wasted (Uma got second billing over Sean Penn, and is hardly in the movie!) Not a Woody Allen masterpiece, but fans could do worse.