I bought this book as part of my study material for the CFII exam at the FAA FSDO, as I will use a C-172 equipped with the G1000 avionics.
Even if I have several hundreds hours on this plane, this book is showing me very useful information about the avionics, especially about how to use the dozen of functions. This will likely be a good point for my checkride, since the examiners like to put you in the corner by asking lots of questions about these functions during the flight, and ultimately that is what students do all the time.
From a more general perspective, this book helps understanding the advanced avionics systems, not only the G1000, so it is a valuable method to approach those systems if you are transitioning to them from traditional flight instruments.
Still the official user manual of the advanced avionics installed on the aircraft is essential to fully operate its complex functions and to have a deep knowledge of their operating principles.
I wish I had this book when was a student pilot, but I am glad that it is here now.