Overall, "The Guises of the Morrigan" is a great book. It is informative, covers many different interconnected myths and legends, and contains numerous recommendations for more reading, many of which I have added to my reading list. All in all, great information, great book.
I do have to knock off one star for three issues I have with the book:
1: The book really needs a pronunciation key. The many different Celtic, Welsh, Irish, etc. names have no indication of their pronunciation, which can be particularly confusing when several of the people have extremely similar names.
2: The book could really use a visual "family tree", as it were, to map out the numerous historical connections to the Morrigan posited in the book. It's hard to keep track of the players without a scorecard, as they say.
3: Since the book deals with a particular Goddess - Morrigan - and the Morrigan has many archetypal aspects to her, some of the posited "guises" are a bit tenuous. Archetypes often appear in totally unrelated societies because they contain such common symbolism. While many of the "guises" are obviously related, the connections become more tenuous the further away from the Morrigan's time the "guises" are. A few posit they are "guises" of the Morrigan solely due to the appearance of crows or a tripartite nature to the myth being discussed.
These three caveats not withstanding, I highly recommend the book, especially to history and mythology buffs, and seekers along the pagan or Wiccan paths.