I have already read other anti-Scientology books, like A Piece of Blue Sky by Atack and Bare-Faced Messiah by Miller. Hill's book is quite different: it offers a very intimate and personal account of what it was like to work, essentially as slave labor, in a large number of Scientology's different organizations starting from age 6. Hill recounts the abuses of the religion while recalling the details of being a young girl, growing up, and discovering love. Being David Miscavige's niece, she had access to the highest levels of the group.
Reading it brought home how similar Scientology is to other totalitarian belief systems, like the Communism of the Soviet bloc, and (to a lesser extent) Christian Science, Mormonism, and many forms of Christianity. Scientology uses all the classic mind control techniques, including indoctrination at an early age, a pervasive organization of spies and reporting, verbal and physical abuse, and so forth. It is very, very dangerous.
I also find it fascinating how Scientologists can rise to prominence in their organization without ever hearing the details of Scientology's completely insane theology. Of course, Christianity's theology is unbelievable, too, but there are different degrees of insanity. To use a mathematical analogy, Scientology is uncountably insane, while Christianity is only countably so.
I definitely recommend it for anyone interested in cults in general and Scientology in particular.