I've had this book for about two months now and found it to be very helpful. My initial surprise was that there wasn't actually much information per page--the authors like to include a lot of extra space per page or fill up half of it with an enormous graphic of something simple like a few elementary shapes or a few lines and points. So when you see that this book is over 1100 pages, don't think that you can actually master Revit with this book alone. Some of the peculiar behavior of revit that we run into over and over again isn't always covered in this book. For example, they will explain step by step how to import geometry from other software but won't give you enough information to know how to troubleshoot an error when it doesn't work correctly or your imported geometry won't accept object styles or whatever it might be.
So although the book isn't as comprehensive as it suggests, it's very well written and easy to follow. I struggled with Revit for a month or two using online resources before I finally bought this and wish that I did much sooner. It helps you understand why you should do things a certain way and has lots of tips for best practices. More often than not, Revit refuses to be intuitive so you need good learning resources and references. Consider it an investment in preserving your own mental health.