Naturally, that initiative must be understood according to the political peculiarities of the time. Philippe d'Anjou ascended to the throne of Spain championed by his grandfather Louis XIV. After a long and bloody war against the Austrian claimant, Philippe managed to secure the Spanish crown, but had to renounce his rights to French succession.
The regent feared that d'Anjou would now take advantage of the monarch transition in France and disregard the renouncement. In this sense, marriage came off as a quite convenient diplomacy tool.
Louis XV was married to Anna Maria Victoria, Philippe d'Anjou's infant daughter. The regent's daughter, Louise Élisabeth, coupled with Louis of Spain, Philippe's eldest son. The regent's choice for Louis XV was not unopposed, though. The perfidious Prince de Condé, another grandson of the Sun king, wanted an older match for the boy, so that an heir could be produced quickly. For reasons I won't spoil here, the unions don't flow as smooth as idealized.
So, given that introduction, let's move to the movie itself:
-"L'échange des princesses" is monotonous. It has too much of a contemplative nature and very little motion -I couldn't identify the climax at all. Were this movie supposed to be a philosophical or experimental work, that wouldn't be an issue. But it's as formulaic as most historical dramas.
-The sequence of events is cartoonish and superficial. We viewers are limited to the uninteresting daily life of royal people and their repetitive, silly feelings. It seems like the director just didn't care about building a solid grid of events. He decided the synopsis should be more than a prelude to the movie; it should be the movie itself! A few additions were made, but nothing relevant enough to keep the viewer awakened. We know the end from the middle and the director puts no effort in surprising us. Of course, movies based on history are always prone to that; but here the issue is just blatant.
-I didn't spot a single miserable soul on screen. No beggars, no smallpox victims lying on roads, no hunger-ridden peasants, no despicable living places -you know, all stuff you expect to see in a minimally critic movie on pre-revolutionary France. One might argue: "Well, this movie is supposed to be about the royal world; you can't blame the creators for not going political". But they went political. With varying degrees of subtlety, the director sought to expose the subjugation of women and LGBT individuals, for which I don't criticize him -au contraire. He made a very good job in that sense. Women being treated solely as children-machines, for example, is a chauvinist issue quite evident in "L'échange des princesses". But I find it rather strange that the inequality of classes, so terrific in the framed period, was just forgotten by the creators.
-Costumes were great: varied and immersive.
Overall, this is movie is watchable. It's a nice pick to watch with family. But it's not good, unfortunately.