The book is somewhat strange. I think that a lot of adults on either side of the Atlantic have opinions about Rumsfeld. Were you to ask them, they'd probably describe him as some sort of Machiavellian Wizard of Oz, who was pulling Bush's strings behind the scenes, along with the likes of Dick Cheney. I think that people who read book will change that view. Was he a conservative defense hawk who what to the right of his party? Probably, but he probably wasn't as right wing as you might think. Was he able to see a more nuanced position on the issues of the day than you might think? Definitely. It's because of this, that I say you'll probably grow to like Rumsfeld more during the first half of the book.
This having been said, having established himself as nuanced politician with a lot of common sense, he goes on to wreck this image.
On some cop shows, detectives sometimes joke that a particular baddie is using the "Shaggy Defense" (courtesy of the Shaggy song "It wasn't me"). That's the approach Rumsfeld takes in the second half of the book. He accepts a teeny-weeny piece of criticism for himself, but passes most on to Paul Bremmer, Condoleezza Rice, Colin Powell, and certain segments of the army (like the officers who suggested the most junior general to lead the coalition in Iraq). It's that area of the book that I found irritating. If Rumsfeld is to be believed, a guy who had been the CEO of 3 huge companies couldn't get on top of his subordinates in the Pentagon? I mean really, please.
In short, it's not a bad book, it's just slightly infuriating. You'll want to throw the book across the room sometimes, when his "buck passing" gets too strong. It's for that reason that I've only giving the book 3 stars. Don't get me wrong, it's well written, and you'll probably end up liking the guy. It's just it'll irritate you too.
Incidentally, I call it a "sort of biography" because the book mentions his early life, and his role in private enterprise, I'd argue that the book felt as if it mostly focused on his "political life" as a congressman, White House aide, envoy and Secretary of Defense.