It can sometimes sound cliched to describe a film as being 'important,' but 'Milk' is an important movie, and there's no better way to describe it. As a frank and factual retelling of pivotal moments in the history of America's gay rights movement, it's never been bested by any other movie before or since. That's why it picked up two Oscars, namely 'Best Actor' for Sean Penn, and 'Best Original Screenplay' for writer Dustin Lance Black.
If you're unfamiliar with the tale, 'Milk' is a biographical film about the life of politician Harvey Milk, who became the first openly gay person ever to be elected to office in California, where he served on the San Francisco Board of Supervisors. Penn completely vanishes into his role as Milk, imbuing the character with a deep humanity and tenderness, which makes his ultimate end all the more tragic to see.