In this book, Samuel Leuenberger offers us a very helpful survey of the history and theology of Cranmer's Book of Common Prayer 1552 and the later 1662 BCP. In the latter part of the book, he takes up a discussion of how the Anglo-Catholic movement moved away from the theology of justification by faith alone and sola scriptura found in the historic Prayer Books to embrace an incarnational and pluralistic form of theology, which has greatly impacted latter day Anglican liturgies, especially with the rise of the ecumenical movement in the 20th century. At the end of the book, he compares the Alternative Service Book of 1980 (comparable to the 1979 BCP of the Episcopal Church) with the 1662 BCP, noting the theological significance of the changes that were made.
Overall, this is a very helpful book for anyone wanting to better understand Reformation Anglican theology as presented in the historic Prayer Books, and how the theology of the Church of England (and the Episcopal Church in America as well) has changed since 1662, and often times not for the better.
If I had one critique of this book (and this is why it gets 4 stars instead of 5), it is that Leuenberger has a tendency to conflate faith with "making a decision for Jesus" and to impose that idea on Cranmer and the other Reformers. A more careful reading of Cranmer et al. would show that they do not see faith as "making a decision for Jesus" but as a gift of trust that God graciously grants to repentant sinners.