I read this mystery fairly soon before beginning my quest to read all of Christie's mysteries in publication order, so when it came up again I wasn't terribly excited. I remember exactly who the murderer was, I remembered exactly how the murder was accomplished, and I even remembered most of the ancillary characters fairly well, including the primary red herring.
But from the first instants of Nurse Leatheran's narrative, I was glad I didn't skip it. Unlike Hastings, Nurse Leatheran is a real person from the instant she steps onto the stage, and that makes her a much more interesting narrator than Hastings ever was. She was always a character, rather than a caricature.
All of the other characters are well-drawn in this mystery as well. Yes, as always with Christie, Poirot can sum them up in a few sentences -- but those sentences were interesting ones for most of the people involved. No one's motives were exactly as the reader is led to assume, and the twist in the resolution is a fine one.
All in all, this is definitely one of the strongest Poirot mysteries. All it lacks is a little of the emotional punch that Christie developed later on in her career -- given that I might have considered it the equal of The Hollow.
I love Christie's archaeology mysteries, her descriptive narrative of the particular culture and place she was writing about always makes me feel like I'm there.