am 28. April 2014
Basically you are building a "book store" App during the book, and while i don't know if it covers everything you can do with Marionette, it is pretty expansive - especially for a book with only around 100 pages. I did not know Marionette before so i don't know if there is more to it, but it looks like every aspect of it is covered and it tells you exactly how to "divide and conquer" in bigger applications.
The sourcecode in the book could have been improved with some syntax highlighting, but i read most of the pages on my Kindle so i would not have seen any color anyway. Still, in my opinion this ist a must have for code.
It's well explained why and how Marionette makes sense to be used pretty much every time you want to use Backbone, and how you can extend (and organize) Backbone with it. You could just use Angular to get all the stuff you need (Routers, Controllers and whatnot) instead of using Marionette with a lot of dependencies, but that's just my opinion. If you like Backbone, there is no way around Marionette and this book will get you started perfectly fine. It's your only choice anyway, i don't know about any other Marionette book out there :)
-1 star because i like syntax highlighting. although, the code parts are usually small and easy to understand.