I just passed the ACSP today. I must admit, it was harder than I thought but definitely you will have a great chance of passing if you read this book twice or three times and do all the exercises. There might of been five to eight questions that wasn't specifically mentioned in this book but you needed to know from experience. However, this book is not only a test prep but a good way to learn a lot of the capabilities and power of OS Lion. I wouldn't say they are hidden features but you might not know them unless you pick up this book (or if you are the type of person that just loves poking around the applications seeing what every menu and button does.) I can't really recommend this if you are brand new to macs or especially if you are brand new to computers. There are some networking sections that might lose and confuse people. I have been using computers for a while; since school, for work, and I use mac's for personal use. But this book will come in handy eventually if you are a current or potential mac user. I see myself going back to this book for reference in the future.
The one thing about this book is the price, kind of pricey and the next OS release sometime this summer '12. I didn't want to wait and I wanted to maximize my knowledge of this powerful OS and try to make a career out of it!!! Also, for the price, I would expect better graphics and screenshots.
So depending on what you are looking for, this might be a must have book. If you want to pass the ACSP the first time, then definitely get this book. If you want to support macs or become a mac genius, then this is also a must have. If you are new to macs or IT in general, then maybe start off with another book.