You probably have not read my review of "Big Secrets", so you have no idea of my absolute disdain for that work. So the fact that I have pumped my opinion of this one up to four stars probably will not shock you at all.
It's obvious that Poundstone has learned since releasing "Big Secrets". He's learned to tell a better story, learned to create suspense, learned what information is utterly useless dreck and what is genuinely entertaining. Both he and the reader benefit from this a great deal.
He's still making wildly speculative guesses about food contents, but here we get a nice tale about how he went about obtaining a sample of Oysters Rockefeller and sent it to a lab. He's still giving away magicians' secrets, but now we are amused by the little backstory he gives his investigation. Overall, this book is better written and is a better read.
One complaint I still have is Poundstone's attitude. His tone is snotty throughout the book; he is critical of people who don't know enough to dress for Antoine's restaurant, of Disneyland, of magicians in general. Rather than revel in the fun of discovery and slyly let you in on the joke, he uses his words to puncture secrets and deflate them, like an evil older brother spilling the beans about Santa Claus. If you are a fan of Disneyland's Haunted Mansion, his expose' will seem particularly harsh.
"Secrets" is fun and will definitely entertain you. I hope the author continues to learn and grow with each book. If so, I look forward to "Biggest Secrets"