OK I admit, when I told my college Arthurian Lit professor that I'd read and enjoyed this book, he proceeded to give me a quick-before-the-next-class-comes-in lecture about how Marion Zimmer Bradley's "interpretation" skewed wildly from the genre.
But I don't care. It's a difficult book (long and utterly depressing,) but it takes the first in-depth look at both women and the pagan Celtic religion of Britain, which Christianity usurped around that time. Evil sorceress Morgan Le Fay is transfered into multi-faceted Morgaine, a woman deeply committed to her family, especially her aunt, Viviane, half-brother, Arthur, and cousin, Lancelet. Gwenhyfar, the simpering Christian princess, was my least favorite, but even she had some complexity, an unhappy childhood, inferiority complex made worse by her bareness, (and obvious jealousy-issues with Morgaine concerning the womens' relationships with Arthur and Lancelet.) Perhaps the most dour of Morgaine's familial ties is that with her son, Mordred, the illigitimate heir of her brother, whom she foolishly put up with her aunt Morgause, easily the most shallow and greedy woman in the entire book.
Religion-wise, I found it impossible not to root for Morgaine's Avalon, not only because I knew it was destined to recede into the mists, but because it was matriarchal, and so much more comforting to me than the expansionalist, narrow-minded and mysoginistic version of Christianity prevalent during those times. At the end, Morgaine herslf shows the most tolerance and versatility for diverse cultures- she outlives most everyone else, and grows to accept that her mother goddess is now worshipped as the virgin mary. Quite the contrast from the crone-like Morgan Le Fay, whose only purpose is to destroy the kingdom of Camelot.