This movie is deliberately different, all in the service of telling us something we didn't know.
Movies are about movies. The borrow plot, character, lighting, sound editing and camera angles from what went before. Since "Birth of a Nation" introduced close-ups, cross cutting and cutaways in 1915 everyone has adopted that vocabulary for story telling. This movie throws all that out: The camera is fixed and stares at a scene for a very long time. Scenes had to be performed all the way through when they were filmed, because each was done in a single shot.
Movies use telescoping of time to compress the happenings of a long period into two hours. This movie tries to avoid that, depicting mundane tasks in their entirety. We watch Jeanne Dielman prepare a meatloaf, step by step, wash the dishes (her back is to us!), smooth the bed, or go shopping.
Movie use facial expressions to express feelings. Spoiler alert: When we get strong facial expressions from Jeanne Dielman there is a very good reason. And that only happens once in a three-hour, 21 minute film.
Movies use broad strokes to carry the audience along. Spiderman supplements explosions with 3D to keep me occupied. By contrast, this film uses subtle changes. You must watch closely to see what happens.
Most movies come to you. This movie requires you go to it. If there is dullness it is among those viewers who think that because they don't get something it's not there to get. There is plenty here but instead of being served to you it has to be harvested. And it is very fresh.