This was a movie I thoroughly enjoyed. It's a beautiful modern fairy tale, where the morale has been supplanted with a liberal political message: The good will triumph, even in court (which reads strangely ironic). The urge to deliver simple, inspiring truths during the wartime probably helped this picture along, but it still stands beautifully now. The structure of the movie was straightforward as far as I could tell - I'm sure they went by the book, from the point of dramaturgy.
What I found exciting was the devil portrayed by Walter Huston. This creature is effervescent with good humor and when he's listening to the farmer he's absolutely honest about his empathy. He was a delight to follow on the screen. More of his work!
The final jury scene is a classic and at least famous enough to be copied by the Simpsons.