The HERO System Advanced Player's Guide is misnamed. What it should be titled is "Advanced HERO Concepts Guide." For the new HERO player, I think it is a bit much to digest, especially if that person has just started down the HERO pathway. That leaves the experienced HERO fan. For them, this book provides discussions on how to tweak the system in interesting ways.
It is organized along the lines of the core rulebooks (Character Creation and Combat & Adventuring) with chapters discussing these optional and alternative concepts in the same order as the core books. The concepts themselves are a mixed bag. Some are quite clever, some seem useless to me, some are carryovers from previous editions that somehow didn't make it to the core books. The individual reader would have to judge which individual tweak might work best for them.
All in all, this book is truly an academic exercise in how to tweak the HERO System. For game mechanists out there, it would be a very entertaining read. For everybody else, it might contain some useful tidbits. I don't know that I would recommend it to the budding HERO gamer. I don't even think most experienced HERO gamers would find this book more than a curiosity. It is an interesting exploration into the mind of Steve Long, the line editor for HERO Games.
HERO Games books have a reputation as looking like text books. HERO 6th went a long way to change that with beautiful color artwork and an impressive layout. The Advanced Player's Guide is a deliberate step backward. It has no art. Some may consider that a deficiency, but the APG was designed to be a textbook on HERO theory. If you are looking for art, this has none. No good art, no bad art. No color art. No grayscale art. No art period. Just something to consider. ( For myself, the book serves as more of a reference than a leisure read. Art is unnecessary. )
I would recommend this only to those who really like to delve into the deep mechanics of a highly mechanical system.