By Robin McKinley.
The McKinley version of Sleeping Beauty, of course. Humorous and entertaining throughout ("And for ecstatic visions, there was always the illegal eating of fish.") Also quite sweet, but don't prick yourself on the ending: parts of it are quite sad. Also, the first chapter, though still written in humorous style, is a lengthy exposition of the country and how magic works, and various other sections tend to get rather vague on some points. (Six or seven years of developing friendship are somehow condensed into a few pages?)
Also, how obvious a name is Pernicia? I mean, you know who the evil fairy is from the beginning when she shows up to lay the curse, but still...
Worth reading especially if you like sweet fairy tales with (fairly) happy endings, and haven't seen anything but the Disney version, where the princess (and Snow White, too) is completely helpless to do anything. This book is probably set in the same world as Damar, since there is a brief reference to a country of that name (and another to modern Earth), but since I haven't read the Damar books I don't know if this casts any more light on them. Probably not.
Update: Here is a pertinent Bible verse for (the second half of) this story: "Greater love has no one than this, that he lay down his life for his friends." (John 15:13) It rather touchingly lives up to this idea.