The Worst Poirot I've Read

Grumpy reader is grumpy.
Previously, I noted that I was in the process of rereading the Poirot canon. If they all sucked like this book sucked, I'd throw in the towel. Fortunately, The Big Four is a rare clunker by an author who usually provides a good read.
I can't even explain this book. It initially felt like a series of short stories, loosely chained together with an overarching narrative arc that involved four super villains. There was way too much:
And not nearly enough story. And then, the whole thing just jumped the fucking shark. There was a Chinaman. There were twins, yes, twins, no, seriously, twins.
Hello there, massive violations of the Ten Commandments of Golden Age Mysteries (which, for those who don't know them are
- The criminal must be mentioned in the early part of the story, but must not be anyone whose thoughts the reader has been allowed to know.
- All supernatural or preternatural agencies are ruled out as a matter of course.
- Not more than one secret room or passage is allowable.
- No hitherto undiscovered poisons may be used, nor any appliance which will need a long scientific explanation at the end.
- No Chinaman must figure in the story.
- No accident must ever help the detective, nor must he ever have an unaccountable intuition which proves to be right.
- The detective himself must not commit the crime.
- The detective is bound to declare any clues which he may discover.
- The "sidekick" of the detective, the Watson, must not conceal from the reader any thoughts which pass through his mind: his intelligence must be slightly, but very slightly, below that of the average reader.
- Twin brothers, and doubles generally, must not appear unless we have been duly prepared for them.
She did manage to wrap up the ending in a reasonably satisfactory fashion. But still, this was the worst Poirot I've ever read. Ever. Read.
Note: I hereby nominate Mike Meyer's left eyebrow for an academy award.