I bought this book because I had trouble understanding how many people are playing in the big MTTs nowadays. I had read the first two Harrington books on tournament play, but I felt like the game had changed a lot since the days those books came out. I was puzzled about the way many players were winning lots of chips with mediocre holdigs. This book helped me to understand better what was going on in the tables. I can't say that I've become a better player, but I hope that when these concepts sink in I can start to gain some success in the tables.
The book has lots of interesting topics like stealing from UTG, calling early raises in position with suited connectors and pushing short stacked with seemingly bad cards. Theories are backed with mathematical equations. In the first reading these things were a little too hard to get a grip, but more studying is required and hopefully these things fall into place too. It's also good idea to read about the tournament play after several years of Harrington's books, because those techniques are so common and everyone knows them so they are losing their power. It doesn't mean they're obsolete but just a little too common and well known that something else might work better at the moment.
To me the last part of the book, which is about short handed cash games, is unnecessary. I don't understand why the authors have added that obviously too short section on complex matter which deserves its own book.
So if you're playing tournaments and want to develop your skills to more advanced levels you need to know these things. After reading the Harrington books this is a good supplement, because this is newer and goes beyound the basics. I recommed this to everyone playing NLHE tournaments. However, in order to better understand these ideas, it would be good to have some kind of basic understanding of tournament play. Maybe not the first book you should read about MTTs.