"Hasn’t life taught you even now that you can’t own other human beings body and soul?"
I love the atmosphere of this novel, it has what I usually love in a Christie book, but I could actually guess the murderer this time after a while. And though I did enjoy it, I had a couple of issues with the novel as well.
First of all, for a Poirot book, we have very little of the character itself. He doesn't do much except receive information from certain people and the inspector, we see him in maybe 3-4 scenes before the final reveal, and that's it. I usually like it best when we see him getting more active, his thought process and his actual involvement - interviewing people, being part of the ambient in which the murder ocurred and all that.
Secondly, I deeply disliked two of the main epicenters of the novel - Henrietta and John Cristow. I think this last one is the worst, since he is the victim, but I actually liked that he died because he was a shitty human being and insufferable. I don't get Henrietta's fascination for him and her insistence that "he was a good man and good doctor", because he a) cheated on his wife without a care in the world (and Henrietta is a hypocrite, because she was an willing participant in this and still said she cared about Gerda...I MEAN) b) actually dispised his patients and his job, he was in it for the money and prestige. The only patient he actually cared was Mrs. Crabtree, because she was going to give him the breakthrough he wanted.
So, since I didn't care a whit that John died, I didn't care much about finding the killer and was more invested in Lucy's antics and the Midge/Edward drama. I also felt that David was supposed to be interesting, but was pushed aside to make way for other things and ended up forgotten and therefore wasted as a character, coming across only as annoying.
So, overall, it had the makings of a great Agatha novel, and everything to be one of my favorite of Poirot's, but ended but being just an ok novel.