I downloaded the first chapter as a sample and - after reading just a few pages - bought the book and moved it to the top of my reading list.
What a disappointment. Harkness has certain charm that occasionally shines through in her writing, but the story is a mess. Villains appear and lurk in the shadows. The heroine goes rowing. Twice. She goes to yoga a couple times, too. The villains multiply. The heroine goes horseback riding. Three times. Then she learns to make an herbal tea.
Oh, and she falls in love. With a vampire, of course. Annoying "mon amore!" crying love. Eyerolling, "Will you ever stop surprising me, mon coeur?" kind of love.
Then the heroine discovers her powers. Naturally, she is the most gifted witch in generations. Here is a partial list of her powers (so far): flight, precognition, talking to ghosts, control of water, telekenesis, control of witchfire (you can't put it out, or heal its burns), and teleportation. Did I mention time travel? Time travel. So she's pretty tough, right? ...No. She does kill one vampire after it wounds her lover, but mainly she wanders around in a kind of daze, remarkably unconcerned by the strange and violent turn her life has taken.
Anyway, I stuck with it to the end, only to find that I could have put it down at ABSOLUTELY ANY POINT and had as much closure as the "ending" provided.
Other reviewers have compared this to Anne Rice. Anne isn't my favorite writer either, but she should be offended by the comparison.
One last note: I'm kind of appalled by the number of reviewers that think this book is smart, or "brainy." It's partially set in a university and it has some scientific words. Like... mitochondria. Whoa! Heady stuff! Not.