For 13 months in 1933–34, John Dillinger robbed banks all over the Midwest, leaving behind a legend and contributing to the growth of the FBI. Johnny Depp gives a charismatic performance of a ruthless and audacious killer, who endeared himself to the public as he liked to give money back to the customers of the banks he was robbing. Christian Bale is the cold, efficient lead FBI agent, in charge of a brutal and not very competent team, little better than the men they chased. Marion Cotillard is Dillinger’s girlfriend who he’s willing to brave all to be with after he breaks out of jail.
Ebert says the movie is well-researched; I’ll take his word for it.