The first half of the book consists of pretty much a chapter per century, starting with the original sources and then walking through Geoffrey of Monmouth, Chretien de Troyes, Malory, and so on. This part seemed consistently excellent, to me. The second half is much more patchy, consisting of chapters on different themes in Arthurian literature, such as the relationship between Christianity and magic or the attempt to map the Arthurian legend onto the real geography of Britain. Some chapters are really interesting and others... less so.