As is expected of Michael Mann, the gunfights were top notch with great sound effects and lots of fire. As someone who holds great interest in John Dillinger and 1930s gangsters, I must say Michael Mann's dedication to accurately portraying the Dillinger arsenal is exemplary. Michael Mann is a gun-nut's director.
The acting was great. The actor playing J Edgar Hoover really showed how Hoover would bypass moralities and anything else in order to catch his targets and gain respect among the government for his still-tiny Bureau... and how much of a jerk he was. Johnny Depp and Christian Bale are great in the movie.
However, the movie opens with the death of Pretty Boy Floyd - Floyd was killed 4 months AFTER the death of John Dillinger.