This is an odd entry in Christie's canon. My reaction to it is similar to yours. And I'm definitely with you on Hugh Fraser as a narrator!

I had no idea how this was going to end and Dama Agatha bushwhacked me with the ending in a similar way.
Hugh Fraser's narrations of the novels are definitely a great way to experience them. :D

That ending... The book itself was kind of dragging for me, because I wan't entirely sure where the story was going, as well written as it is. And then all of a sudden, I was like, "Wait. What? What just happened?"