I think it's a good idea to note that the movie, while nice, and having loads of great music (though some prefer other performers of this repertoire), is not based on a whole lot of actual fact.
This isn't necessarily a problem, of course - many a wonderful movie is completely fictitious! But I know a number of musicologists and historians who get somewhat annoyed at the number of people who take the film to be based on actual events, when in reality, we know almost nothing about Sainte-Colombe, and not a huge amount about Marais either. We don't even know Sainte-Colombe's first name!
That said, I think it's great that a movie can be made, and that meagre facts can be elaborated into a full story. But, like Amadeus, Immortal Beloved, Farinelli, and almost every other film about classical music, most of it is an invention, and in most cases, the facts as understood by musicologists (not to mention modern performers of the music!) are quite different.