I guess in theory it's an interesting choice to shoot a gangster film with handheld camera in HD digital, to give it an immediate feel, but in practice it makes the film look cheap and ugly. It looks like bad TV, with lots of close-ups. Boardwalk Empire looks better and more cinematic. And Johnny Depp's Dillinger is completely uninteresting as a character. Possibly the film is closer to reality than previous portrayals of the guy, but that's no excuse to tell a boring story. Maybe it's a genre that needs to be told in a more operatic style, like De Palma.
Top five Michael Mann movies:
4. The Last of the Mohicans