Maybe "All the King's Men" is a bit long in the tooth now, but until "The Godfather" and "Patton" it was the best film ever made!
The selection of Broderick Crawford as Willie Stark was gutsy, since Crawford can -at best- have been considered "good". Somehow, though, Crawford did not play Willie Stark - he Was Willie! Much like George C. Scott did not play Patton - he Was Patton.
The "you hicks" speech was great. Not until the "Patton" speech was there anything better on film.
Essentially, the thing making the film great was watching Willie "grow up" in the sense of casting aside his idealism for power. Turning point is the cemetery scene, when one of the attendees seeks divine forgiveness for not having voted for Willie.
The turning moment was not unlike Michael Corelone saying "I'm with you Pop" when the Godfather was in the hospital. Michael did not mean physical proximity, but that he then "bought into" the business.
In both cases, the storyline is a reminder about Power and Corruption.
Like most movies made from books, there were some changes that did detract from the story (no where in the movie do we learn that the Judge is Jack Burden's father - yet that is so important). Yet, correspondingly, no one can accuse the book of word economy. It is a powerful story, but overly descriptive.
Crawford's change of expression - the beginnings of insight - are classic.
Definitely worth seeing.