This film completely took me in, the simplicity of the set-up was a bit discouraging at first. But when the very resourceful Helene is slowly stripped of her social defenses and comes to display her true, evil personality I was already siding with Agnes. The young dancer represents life, a very interesting version of rebelliousness, and a definitive disregard of the upper social class - which is an obvious consequence of her lifestyle.
That the film still manages to come to a fairy-tale like and beautiful ending is testimony to Bresson's genius. Although the story becomes less and less "realistic", I couldn't care less. After the viewing, I was just happy that everything came out as it should (in a way). And not too many films leave such a warm and satisfying aftertaste.
Worth for studying the character development, "peeling" of the motives.