[Book Spoilers] Book deviations in this episode

[Nezzer]

I think this was merely compression of the storyline. Stannis does start off the post-Blackwater period in a funk - he allows the burning of several of his bannermen before Davos arrives. I think they're just trying to convey that period in one brief scene before presumably Stannis steps up to the plate.

Yes, this is the lowest point of Stannis's campaign. Like Salladhor Saan said to Davos on the ship, Stannis is a broken man. Even in the books he let Melisandre do everything she wanted before Davos arrived. I think he's still pretty in character so far. He will still rise again back to his old self.