TLDR: Don't bother.
This was a surprisingly bad execution of Herman Koch's novel The Dinner, which I read a few years ago. I enjoyed the book--this even despite it employing one of my least favorite tactics. The novel centers around two couples going to a fancy dinner--a former teacher and his wife, and a promising candidate for governor and his wife. I liked how the book rolled into the scene, quickly making you think that the main conflict is between Paul (the teacher, who is antagonistic towards his brother), and Stan (the politician). As the seemingly unendless dinner unfolds, you find out what the real conflict is: that the couples' children have done something really awful, and now they must figure out what to do about it. There are some reversals here which are interesting.
Both the portrayal of the characters and the dinner itself are very good. Sad when you have a really competent cast and then give them crappy material. Steve Coogan plays Paul so effectively that I don't think I've ever wanted to scream "Shut the fuck up and let him talk!" at a TV more. He is the obnoxious relative that just can't keep his mouth shut when he has some political opinion, or wants to distract the argument from the point someone else is trying to make. You start out almost being sympathetic with him--a more humble man that thinks going to an ostentatious tasting menu (and then asking for a better table) is what's wrong with society. But then he spirals down from there. The other three actors are also good, Richard Gere in particular.
The dinner itself is appropriately portrayed in a way that is infuriating. Occasionally you glimpse these super-bougie dishes and have to sit through the long explanations of the dishes. (This reminded me of the incredibly tense scene at the Mexican restaurant toward the end of Breaking Bad--where threats abound until an oblivious waiter pops in to offer guac.). You kind of want to pull your hair out because no one attending the dinner can actually sit in their goddamned seat for more than two minutes: someone is always taking a phone call, storming off, or just wandering away. (I hope they left a very, very large tip.) The dialogue is also good-- people talk over each other, things are alluded to but not explained for the sake of the reader.
But the movie definitely falls flat when it comes to the fundamental skeleton of the story. For one, it's too long and there are parts where you wonder "why is this here?" There are also parts where I wondered "why did they cut this out from the book?" (SPOILER: mainly, they definitely made it seem like Paul had some mental health issues, but did not explicitly draw the connection to his son via the test results. Also the movie version of his wife says that his medication makes him "numb" and that she prefers the real him, but in the book this definitely comes off as more sinister/ fucked up, and less like "maybe we should try a different prescription. Also the ending, ie, the book had one). There's some scenes about the Civil War that were so long that I fast forwarded.
Then the end, where it falls flat. It literally ended in such a place that when the credits started rolling I went back and rewound, thinking there was something wrong with my TV. A movie with no ending is worse than a movie with a bad ending because at least you feel like you got to a destination.