Goodrich tries to do justice to the Merlin ethos, succeeds in some places, and but in the end the reader is left with more questions than answers. She does not fall into the area of lunacy, which can happen with a book like this, but niether is the pure history.

Personally I enjoyed fantasies about Merlin more than I did this book.

Wikipedia:
She adopted the view that the 12th century pseudo-historian, Geoffrey of Monmouth had known that Arthur had not been in England, but in Scotland, but had concealed this unpopular view by listing the names of Arthur's battles in Latin rather than Gaelic—the original Celtic language of Scotland. “When I finally figured out what he was doing, I translated the Latin back into Gaelic,” Goodrich told the Riverside Press-Enterprise in 1994. She then found that the names coincided with places in Scotland. (The conventional view has always been that Geoffrey was describing places in southwestern England or Wales.) From her analyses of ancient languages, Goodrich discerned that Guinevere was a Pictish queen and Lancelot a Scottish king.

Goodrich's books were infrequently reviewed in scholarly journals and generally ignored by academic authorities.