As a lifelong AC fan who finds something to enjoy in almost all her works, I like this tale and find it quite moving. I've always loved the dynamic between Poirot and Hastings and their spikily affectionate exchanges, so this being the last Poirot novel is poignant for me. AC's books are always readable, amusing and wise. When she is at her best, her work is timeless. Probably why I hardly ever see her books in charity shops.
There are gaping holes in this plot, bizarre motivation of the killer, the whole premise is unlikely at best, and weak characterisation (I found Hastings' daughter Judith particularly irritating)but it moves along at a fair pace, Poirot is as sharp, perceptive and wry as usual and Hastings as kindly, well-intentioned and misguided.
Classic nostalgia where people greet each other with "hullo", "queer" used to have a totally different meaning, a sinister lothario Major, saucy nurse(the obligatory redhead for Hastings to admire :)) tisanes, drugged hot chocolate, and lamentations about English cooking...back in the original setting where Poirot and Hastings first met decades ago. What's not to like?
As a sucker for AC's classic 10-15 people whodunnit, each with their own secrets, where things are never quite as they seem, I cannot help but enjoy Poirot and Hastings together for the final time, back at Styles. I re-read each of my 70 AC novels every 5 years or so, and I never stop enjoying them. There'll never be another writer like AC for me.
Far from her best, but still enjoyable.