This review is going to be one big spoiler, so stop reading if you've not read this final Poirot. But I have stuff to say!
First, this one was narrated by Hastings, who was a recurring character primarily seen in the earlier Poirot mysteries - he met his wife, "Cinderella" whose real name is never disclosed, in book 2, Murder on the Links. After marrying, he moved to Argentina with Cinders, returning to England sporadically. In Curtain, Cinders has died, and Hastings is a widower with three children, including the annoyingly terrible Judith who figures prominently in this book.
I've never really found the friendship between Poirot and Hastings convincing until this book. Hastings is an ever so ordinary British, stiff-upper-lip sort of fellow. I finally became convinced of the affection that Poirot had for Hastings through the events in Curtain.
This was a brilliant finale for Poirot - who has the unique characteristic of being the only fictional character to ever receive a full-page obituary on the front page of the New York Times.
And so, the curtain falls over Poirot, and I have no more full-length Hercule Poirot mysteries to read the first time. As a character, he was priggish, conceited and frequently insufferable, but likeable for all that.
Well played, Dame Agatha. Well played.