You really don't need to read this book to do a 100 Thing Challenge. I picked up on the idea as an Internet meme about 5 years ago, then spent two years traveling with rather less than 100 things in tow. That's the easy way to do it, of course, but I hate having too much stuff anyway.
So does the book have any value add for those who already know how to count things? It's very much about Dave Bruno's personal experiences with the challenge after he originated it - and not really a how-to, for those who need help decluttering. It's modest and undramatic, but a pleasant and easy read. In his shoes, I would have had so much to say about owning stuff, historically and culturally, which he didn't say and perhaps doesn't know. I do think the book could have been more, but such as it is, it amused me.