Simply "wow". This movie was a complete and utter emotional roller coaster from start to finish. The story, adapted from the short story (of the same name) by F. Scott Fitzgerald, is that of a boy who is born as an old man (in baby form) that grows younger as others (naturally) grow older.
Benjamin's mother dies after giving birth to him, and his entrepreneur father thinks of him as hideous. This results in Benjamin being nearly thrown into a river, but after a being chased by a police officer, Mr. Button decides to just abandon his son on the steps of a stranger's home. From there, the story takes off in every possible direction that it can. Benjamin learns to walk, grows [white] hair, works on a boat, falls in love, and more, all while growing younger and younger.
TCCoBB reminds us all what it is to be human and how we grow as individuals through time. Love, forgiveness, apathy, heartbreak, anger, etc., are all explored in eloquent detail. Bring some tissue; it's a tear jerker.