This book came highly recommended, so I'm sorry to say that despite its strengths, it has not inspired me to seek out the 15 sequels.
For a fantasy novel first written in the 80s, this has aged reasonably well, though not so well as another recent find of mine, the wonderful The Ladies of Mandrigyn. Daggerspell is listed as epic fantasy, though there's no more than a hint of an Enemy--as opposed to a mere antagonist--in this volume. While Kerr incorporates some old-fashioned elements (I can't remember when I last read a fantasy book that actually included elves and dwarves), the plot is an unusual one, with the first half following the same group of main characters through multiple incarnations over the span of four hundred years. The second half focuses in on the "modern-day" plotline, involving the rebellion of a minor lord against his prince.
But if the plot is innovative, the characters are standard fantasy creations: Jill, the Exceptional Girl; Rhodry, the Noble Prince; Nevyn, the Wise Old Man; Cullyn, the Swordmaster with a Dark Past. They aren't flat, but they never did much to grab my attention, and while seeing the variations in their love rectangle in their several incarnations was a novelty, I didn't find said love rectangle nearly interesting enough the first time to want to see it repeated twice more. And the "star-crossed lovers" rationale is used to shortcut through actual relationship development, making it hard for me to care about these supposedly life-altering passions. The rebellion in the latter half of the book interested me more: here the story moves at a brisk pace, with enough political complications to please those who prefer intrigue to fighting in their fantasy. It is also nice to see characters who are reasonably quick on the uptake: when there's a "no man can kill him" prophecy about an opponent, I worried they'd be lost for half the book, but it only takes a few pages for the guys to appeal to Jill.
The story takes place in an alternate version of medieval Wales, and Kerr's worldbuilding deserves the praise it's been consistently given; much fantasy takes place in "quasi-medieval" worlds, but this one feels like an authentic medieval setting, as well-researched and thought through as historical fiction. The physical and political details of the world ring true: initially I was surprised, for instance, at the small size of the warbands, but for local chieftains with limited resources at their disposal, the numbers make sense. The dialogue is somewhat stylized, but in a consistent way that gives appropriate flavor to the characters' speech, and the writing style is adequate.
In the end, a competent fantasy with textured worldbuilding, but rather staid character roles and personalities that left me uninspired. While this book has an independent plot arc, it's clearly the first in a series, with many loose ends and a story that, standing alone, has little resonance. I wouldn't discourage others from picking this up, particularly those who love long fantasy series, but as for me, I'm unlikely to continue.