George Orwell underestimated the politicians of the 21st century. In 1984, the blunt tool of "doublethink" used simple opposites; the ministry for war was called "the ministry of love", for instance. But doublethink can easily be translated back into English, you just reverse it.
Unthink is more sophisticated, here the ministry of war is "the ministry of defence". Surely a body tasked with defence can never do anything bad or offensive, because defence is morally justifiable, right? The principle of unspeak is to persuade by stealth, to alter assumptions inherent in the definition of things. Who are you more afraid of: a "suspected terrorist" or a "terrorist suspect"? The former emphasises ambiguity, the suspicion that they might be a terrorist. The latter emphasises the terrorist as the definition with suspicion as an afterthought.
At an even higher level of sophistication though, an unspeaker can play language any way they want. So the proponents of "intelligent design" state that creationism is a theory, and as such has as much validity as evolution. However, in the case of creationism they are elevating it to the status of a theory. In fact, it is no such thing as it is not falsifiable, has no supporting evidence, and has no predictive value. But by defining it as a "theory" they are reflecting in the glow of scientific terminology. In their attacks on "neo-Darwinists", however, they say that evolution is "just" a theory, and here they use theory in the fluffy, not quite sure, kind of sense. It's a cunning trick.
If the examples above turned on any little lights in your head at all, you have to buy this book. Steven Poole has a rare and valuable talent in non-fiction; he writes sentences that makes you say "Yeah! I had a vague inkling about that too but he's gone and put it into words!"
I will agree that there is a lot of focus here on the Iraq war and George W Bush era of politics. However, had the author written a book about the rape of language but neglected to quote Donald Rumsfeld at every turn he would be doing his readers a great disservice. The Neo-cons have made Catch 22 a reality, and named it "Operation Enduring Freedom". It was going to be called "Operation Iraqi Liberation" but then they realised that the acronym for that was OIL. Enjoy.