This is an entertaining "history" of the FBI, but it should be viewed as fiction, because that's exactly what it is. What else could it be when J. Edgar Hoover personally approved and had a cameo role in the production. James Stewart is excellent, as usual, and the supporting cast, except for the talentless Vera Miles, is good. Murray Hamilton is especially good in a supporting role as Stewart's partner and best friend. The FBI accomplishments that the film highlights are undoubtedly all true. What is significant is what it leaves out.
One of the most shameful parts of the film is the depiction of the killing of John Dillinger. It is portrayed pretty much as it happened, but no mention at all is made of Melvin Purvis, the Chicago Bureau Chief who headed the operation. Instead, the operation is depicted as if the fictional Chip Hardesty were running it. It has been said that Hoover was jealous of the publicity that Purvis received after Dillinger was killed; Purvis was subsequently transferred to a remote outpost, and shortly afterward left the FBI. This is no doubt why Purvis was never mentioned in the film. But this viewer, at least, paused to think that if Purvis was treated this way, what about all the agents who conducted all the other operations depicted in the film. Were they also completely ignored and replaced by the fictional Hardesty.
The film is probably accurate in its portrayal of FBI activity up through the end of WWII. However, after that point, the film would have us believe that the only threat facing the US came from international communism, which is no doubt what Hoover believed. Never mind the Mafia. Never mind the lynchings that were still going on in the South. Never mind that blacks were being intimidated to keep them from voting in much of the South. I don't know if the FBI had started wiretapping Martin Luther King by the time this film was made, but if not, it wasn't very long afterward that it started.
As I said at the outset, this is pretty good entertainment, but it should be viewed as the sanitized fictionalization that it is.

I do not know if this movies problems are more the fault of Direction or Script. As you will see in many reviews the editing style is way overdone. It is absolutely distracting and without substance, which could be considered a good thing if you look at some of the quotes from the movie. I do not write many reviews here, but felt this movie was so awful that it deserved comment. Movies like this erode at Movie making as an Art form. Movies like this one show more and more clearly that the current Reality focus in cinema is revealing the quality of the characters behind them. People hone there craft, there 5 senses, and there business sense - overlooking there own inner life. However I do not put blame on them, it is more and more the unfortunate condition of this age - qualified by films like this one. But by proxy these Manufacturers I would dare not call Artists vomit there lack of inner life or regard onto the screen - diffusing it to everyone. A story of bounty hunters, guns guns and more guns, heavy handed flaunting of sex - for the oh so popular actress (did they write the lap dance scene after they signed her?), over saturated, over exaggerated, one liners, non-linear plots. All different and yet all the same. Annoying overwhelming music to push the emotion down your throat. A story? a development of character? or just withheld, missing information, revealed at the end to create the *effect* of a story - as if one took place. It altogether lacks anything remotely resembling subtlety. It is a caricature of stereotypes and genre. Where are the films with Awareness? What about subtlety of sound and music that you are not even aware is there? What about the depth of a look? What about editing with a point about mind and consciousness? yes even in action films this can happen. Sure they have honed a craft; but what use is it without soul or wisdom? of insight into the human condition? Can the people who commented and said that this is an apogee of art, or compare this to Picasso and others - I say put this next to Gandhi or the Godfather, even the original trilogy of star wars or the lord of the rings; then look me in the face and say it again. It is a good crew, but they need some help with depth and story. I hope they get it because I like the crews previous work. better luck next time.