Jon Krakauer wrote a brilliant piece of journalism in his work about Christopher McCandless, who went 'into the wild' in Alaska and did not return alive. He explored the ambiguities and meanings and difficulties of this young man's story with great writing. Sean Penn and his cast and crew have made a companion piece of equal quality in this film. Bravo.
And bravo to the McCandless family, who have let the story now twice be publicly told in ways that do not always flatter them, but that place truthtelling and honesty first.
If you haven't read the book, then do. If you haven't seen the film, then do. Each illuminates this story in different ways.
Roger Ebert's review is here.