Pope Francis looks like he genuinely likes her, which will play well if that image gets to a lot of the world where Catholicism is strong. The whole image is of a very congenial visit. Combine that with the 'most powerful man in the world' standing close to his wife and yet dwarfed by the awesome majesty of soaring ceilings of the Sistine Chapel, devoted to Almighty God, united, humbled, if you will, at the power implicit there, and the combined images would play very well indeed.