It might be considered a novel of hippy-dom in the San Francisco Bay area in the early 1970s. It is also a book about the intrusion of supernatural elements into a modern community. And most of all, it is a contemplation of the ideas and attitudes that in real life created the Society for Creative Anachronism in that same Bay Area in that same era.
Peter Beagle, who enjoys a very high reputation among a certain group of fantasy readers, is in this novel perhaps not as careful to construct a unified work of art as in some others. There are a few weak spots in the book that support that analysis. However, one can also argue that Beagle has got countervailing strengths which allow him to deal with a number of themes in interesting ways. The novel is complicated and diverse, just like life.
My own interest in the book is unsurprisingly in the way he portrays the early SCA (as the League of Archaic Pleasures), not as it was but as it might have been. Beagle says a lot about the SCA, especially the SCA in its earliest days, and he is very fair in his portrayal. He shows the good the bad the mundane and the bizarre that can accompany a serious effort to revive historic activities and culture. Like the early SCA, Beagle's League of Archaic Pleasures exists for good reasons and bad. People have a variety of motivations, not all of them good, and not all of them contemptible either. If you are a long-time member of the SCA like I am, you recognize people thinking and talking about the activities they have taken up and the Society they have created, taking pleasure in them, and wondering whether what they're doing makes any sense. Beagle does not answer their question.
One can argue that this kind of social fantasy is dangerous, and Beagle is quite aware of that. He deals with the dangers by portraying them as age-old supernatural forces that reemerge from elsewhere to intervene in and exploit the favourable environment created by the existence of the League. Beagle is able to make the reader shiver almost as much as the characters in the book do when confronting unexpected and uncanny manifestations.
I was talking about this book to a friend who had had it unread on the shelf for years and realized that my younger friend might find this to be a historical novel about a certain time in California's history. It is after all nearly a half-century old.