_____As a thinker, Shaw leaves much to be desired -- certainly when it comes to matters such as compulsory inoculation. But as a playwright, there's no questioning his skill. This first scene of Saint Joan is exemplary in matters of expository dialogue and characterization, and in the deft use of a punchline ("The hens are laying like mad, sir") at the end of the scene. Granted, we have all become used to this sort of thing, saturated as we are with dramatic formulae from watching TV, but paradigms have to come from somewhere, and Shaw was a master of crafting ways to identify characters and reveal things about them -- the overelaborate stage directions are hardly necessary (and in any case would be unavailable to the audience watching the play in its first performances).
He also has the knack of giving minor characters key speeches, such as in this exchange between Robert and the Steward about Joan:
ROBERT. You parcel of curs: you are afraid of her.Shaw manages to insert his ideas about Joan into the dialogue, as when he has Robert say, "she's not a farm wench. She's a bourgeoise." It is Poulengey who reveals why the French are willing to accept Joan's leadership: She's their last resort.
STEWARD [rising cautiously] No sir: we are afraid of you; but she puts courage into us.
What is the good of commonsense? If we had any commonsense we should join the Duke of Burgundy and the English king. They hold half the country, right down to the Loire. They have Paris. They have this castle: you know very well that we had to surrender it to the Duke of Bedford, and that you are only holding it on parole. The Dauphin is in Chinon, like a rat in a corner, except that he wont fight.... I think the girl herself is a bit of a miracle. Anyhow, she is the last card left in our hand. Better play her than throw up the game.... It is not a gamble. ... It is a certainty. Her words and her ardent faith in God have put fire into me.And when Robert challenges Joan that her voices come from her imagination, she checkmates him (as Poulengey says) by admitting as much: "Of course. That is how the messages of God come to us."
Of course, Shaw's Joan is a good bit more "modern" than the actual one must have been. She is not willing to demonize the enemy:
They are only men. God made them just like us; but He gave them their own country and their own language; and it is not His will that they should come into our country and try to speak our language.... He gave us our countries and our languages, and meant us to keep to them. If it were not so it would be murder to kill an Englishman in battle.... If I went into England against the will of God to conquer England, and tried to live there and speak its language, the devil would enter into me; and when I was old I should shudder to remember the wickedness I did.