I've recently been gifted this book from an old teacher.
It's 95 pages long (excluding the "about the authors" page) and can definitely be easily finished in one sitting. It took me an hour and a half, but that's if you decide to look at the illustrations, which are in nearly every page of this book.
Reading, the vocabulary is not complex and easy to understand. You don't need any prior history knowledge to read. The drawings resemble a more polished version of the art-style in Ronald Dahl's books (although not colored.)
The title is the main subject. Wulffson explains 28 different inventions (e.g.: the pencil, the shopping cart, the alphabet.) Some information is outdated but I still enjoyed reading (this novel is very fun.)
This book is suitable for all ages, but it's probably best you give this someone older than 9. (Does your child know what "scourged" means?)