Public Enemies

James Bowman did not like the movie. I haven't seen it yet, so i cannot comment on many of his points. But i think he let's politics get in the way of history with this:

Mr. Mann commendably refrains from putting the head G-man in a dress, but only because he doesn't have to in the furtherance of his portrayal of him as a publicity hound whose crime-fighting was nothing but a cynical (and successful) attempt to manipulate a more credulous media than today's (and there's another box for us to check). Collusion between government at all levels and organized crime in the person of Frank Nitti (Bill Camp) -- in the murder of Dillinger as in other matters -- rounds out the film's portrait of the Land of the Free and the Home of the Brave in the 1930s for an audience mostly ill-equipped to know any better or to care very much if they did.

It sounds to me that director Mann is true to his source in this portrayal. The book Public Enemies (i reviewed it here)
provides ample documentation that Hoover was a publicity hound and that there was collusion between organized crime and government in the 1930s.