Edgerton's story is mostly a romance, with a rescued maiden and witches and murder and what-all. I liked best the straightforward interior reasoning of the characters. People do odd things in the originals - Owein & Luned, Gereint and Enid and their mutual misunderstandings - and I liked the modern description of consciousness that Edgerton supplies her characters to explain their foolishness.
I think the book would be better for a less matter-of-fact attitude towards all the magic; she has at least two kinds of magic, three if one counts miracles. It's the one place where I think the characters claim to have feelings that aren't supported in the writing. Maybe she was reflecting the straightforward descriptions of marvels in the old stories, but in this book it shows up as a change of tone & in the wrong direction.
The place of the Church is odd in both Castle... and the Mabinogion. People talk about it, and act as though it were a power temporal or miraculous, but neither the Church nor any clergyman do anything interesting. Compare to, say, the Cantigas de Santa Maria, in which Mary is constantly invoked and quirkily active: when a is unjustly accused of stealing some porkchops, the porkchops are found when they begin to dance and sing; when a monk steals altar linen, Mary makes his ill-gotten undies shrink until he sees the error of his ways.
ISBN: 0-441-09275-6
So wrote clew in
SF&F.