It has become one of the biggest blockbusters ever made. Surprisingly enough, it doesn't even feature one car chase, animated dinosaur, or interstellar battle. In fact, this genre of movie, the recreation of a historical event, is probably one of the toughest films to make. Unlike pure fiction, the director has to carefully research each fact of the event and represent these facts as accurately as possible in order to keep his or her audience engaged in the action. Of course, the further back in time the director chooses to set the film, the easier time a director has to pull off his or her magic.
Fewer people have first-hand knowledge of the event.
Of course, the reverse is true. The more recent the historical event, the more people have first-hand knowledge of the goings on of the time. And the audience members will be critical of any inaccuracies. Recently, Ron Howard's Apollo 13 comes to mind as an example of a very well-done piece. Here was an ambitious endeavor.