It is Brilliant but for me N or M is better.
What I love about this novel is that it's the only fictional depiction of the "bright young things" of the '20s I've encountered where I don't feel like I need to take a shower afterwards. I love Waugh as well in his depictions of this generation, but once I'm done laughing, I think: these people are sociopaths, and I wouldn't want to spend more than 15 minutes around them. Also, these types of people are actually usually "bright filthy rich well-born young things." Tommy and Tuppence are ordinary people, people who served their country in the war. And, while many would see the scenario of being "down and out" after having given one's all for one's country a cause for bitterness, Tommy and Tuppence use the conversational style and attitude of the "bright young things" to take it in stride and move on. In that, I think they embody one of Christie's big messages about life: accept it and move on.