McKillip is one of my most favorite authors. I find myself hoarding her books, waiting for the perfect time to read them - because I know they're going to be perfect. (I know this makes no sense, and I will likely die with wonderful books unread due to this horrible tendency.)
McKillip's books remind me of neo-medieval bands (Qntal, Faun, etc.). They are deeply rooted in tradition, but unmistakably new. They are pure without being innocent, complex without being muddy.
That said, some of her books are very similar to each other. Reading Od Magic, in particular, I really felt like I was reading about many of the same characters portrayed in the last book I read by her, 'The Bards of Bone Plain.' Sure, it was a different story, and a different setting - but at times it was almost as if her standard characters had been dropped into a different story. However - I didn't really mind.
Here, a young man, suffering from grief and having lost his way in life, is approached by a mysterious elderly woman who instructs him to travel to her school of magic - they're in need of a gardener. When he arrives, he discovers that while that's true, the old woman, Od, has approached legendary status at the school - she hasn't been seen in decades. The school, on the surface a haven for talented magicians, is drowning in hidebound strictures and politics, and the king is deeply suspicious of any kind of magic that deviates from the ordinary.
When a group of traveling players with an extraordinary magic show arrives in town, suspicion is thrown on both them and on the innocent gardener, and the king demands arrests left and right.
The story is an excellent depiction of fundamentally decent people who often behave less-than-decently due to inflexible rules.