After some dissatisfaction with the much later "Third Girl", I decided to try an earlier Poirot to see what I'd been missing.
"The Murder Of Roger Ackroyd" seems to be the most highly recommended Agatha Christie book. It's also the fourth Hercule Poirot book, qualifying it for Door 13 Advent in the 24 Festive Tasks challenge.
I'm about a third of the way through and very pleased with this book. The writing is assured and confident. The narrator, a local doctor, is a good observer and makes a great foil for the rather odd little Belgian man who lives next door to him. The murder mystery is a sort of amped-up locked room mystery with a wide variety of possible villains and some peculiar plot twists, for example how the good doctor is first made aware of Ackroyd's death.
I think what I'm enjoying most is that, in this book, Agatha Christie has forgone the authorial voice and is telling the tale entirely through the eyes of the good doctor. I wonder if this is a deliberate allusion to Holmes and Watson. In any event, so far it has produced a clearer and more intimate view of what is going on as well as a fresh-pair-of-eyes assessment of Poirot.