This is a good and clearly written introduction in textbook style for anybody who is new to outboards. Or even technical subjects in general, as in some places the book includes primer material on how things like electricity work. All the common systems and components of outboards are covered, together with maintenance and troubleshooting guidelines.
However this is a cursory overview and a serious boater should either find a reliable store to sell them the right brand and model of an outboard and do all the bigger maintenance chores, or - get a second book on outboards for all the nitty gritty details you'll certainly need. For example, the book contains very little information on topics like in which year a particular technology was introduced by which manufacturer, how different outboard brands compare, how to evaluate a second hand outboard, etc.
The book is a bit outdated in places, too. Printed in 2006, the book still views 2000 as "current". For example, it flatly states "the fact that most outboards have two-stroke engines" - which is probably true when you consider all the old 2-stroke outboards out there still running. But for example in Finland, about 66% of all new outboards sold are 4-stroke... Also there is no discussion of the newer software-based outboard technologies, which allow a an engine to tackle some issues by itself, or a mechanic to get detailed data such as how many hours has the engine been run and at which RPM ranges.
But if you are just looking for a crash course in outboards, the book gets the job nicely done.