Aronson is one of the leading researchers in the field, but you'd never know it by the easy style of the book. No real political bias that I could see - in the section on self-justifying war, George W Bush comes under some scrutiny, but so does LBJ. They are quite hard on their own field, too. Their main point is that all humans do this, so checks must be built into systems - we can't trust our own perceptions of confirmation bias.
I read a lot of this kind of thing, too, but seldom make it all the way through the book. This was a good one.