I've had this book for about 10 years. I actually met Mr. Loewen when I was an intern at the Smithsonian (he was doing his research there), and he gave a talk to the interns there. Very nice man. I think I bought his book at the gift shop after the talk.
Lowen analyzes 10 high school American history textbooks to see what they do and don't tell us, what they got wrong and what they got right. His argument, basically, is that the textbooks promote hero worship in American history and what we did in our past was never wrong.
The book was interesting but I did find some parts tedious. I was a history major in college, but I did not know everything he wrote about. He also wrote about why he thinks many Americans are not interested in history.
I have another book he wrote, Lies Across America, which is about what historic sites have gotten wrong.