When I started reading this series I had no idea that it was incomplete, though I am glad it is not, particularly as whilst getting to the end of Blackveil all I could think was that the story couldn't end there, it would have been too rushed, and leaving too many questions. I'm not sure whether or not it is because there is currently no book following Blackveil, but it felt less like a finite ending than the other three books, and the story is definitely not finished! My other note about reading them is that I got distracted about half way through The High King's Tomb, I'd say that this must be because I didn't find it as engaging as the other three books, though after starting the second half of the book I did find that I literally read straight through that and Blackveil.
It is easy to see the development of the writing style and the story, as the books go on there are more and more plot layers and levels, and actually even from the beginning the overlying plot is the same, and appears that will remain so over the rest of the series.
At face value it seems that the main character, Karigan won't-attempt-to-spell-her-surname (or say it), has an awful lot of luck, she goes through a shocking series of events and escapes alive, though she doesn't escape unharmed, which makes it add a little credibility. It works because it is explained how she is saved or how she works it out, and she isn't just a weakling, she can defend herself.
There was also the fact that in the series women and men seem to be equal in the society, there is very little problem with women walking around in trousers, or doing jobs that men would traditionally do in fantasy worlds, this is quite refreshing in the fantasy genre.
On to the love story in the books...well it is very much a background part of the story, it's there but it isn't the main story, and without it the story would still work. At first I was all for Karigan and Alton (as opposed to Zachary) but now I just want to punch Alton (anyone having read Blackveil will understand that!) though I'm still not sure where I stand on her and Zachary.
All of the characters, even those on the sidelines, are well rounded out and feel like real people (well with magic) and it is good to see that 'good' characters do bad things, and they don't get away with it. This is another of those series where good and evil aren't quite as clear cut as you think they are (Mornhaven aside), everyone has a bit of both in them, and even the 'bad' guys, like Grandmother, are doing things for reasons that they think are sound.
You should read this series if you're into fantasy, there are kick ass characters, real emotional complications, and adventure, everything that is needed for a good fantasy!