Outdated. Sloppy. Misleading. If you want to learn geometric algebra, do yourself a favor and avoid this book because it's pure dreck. This book is full of errors (just look at the long errata on the website), and many of the claims it makes about capabilities and performance have been debunked by the real experts in the field. It has also been shown that this book is simply wrong about several important fundamental aspects of geometric algebra, and the writers just didn't know what they were doing. If you already have a copy of this book, the only reason to keep it would be as a backup plan in case of another toilet paper shortage.