I will say that I liked having a closer peek at the thoughts of Hercule Poirot. I do have to contradict Christie's grandson a little bit....it does not read "just like an authentic Christie." 
You can tell that this was adapted from a play, both from the smooth movements of "musical cups" in a pre-murder scene and from the overly dramatic villain speech. It's probably fun to see on stage but translated just a little wonky into a novel. 
I was interested and it moves pretty fast.