I generally stay far, far away from paranormal romances. I have never understood the romantic appeal of vampires and werewolves, I don't like the woobification of monsters to make them more palatable to modern American sensibilities, and I especially don't like the "weak, pathetic humans!" tone most of these novels end up taking.
And yet I kept reading good things about Harkness's A Discovery of Witches,so I bit. And I'm glad I did -- this book was smart and fun. The world-building was fascinating, the mystery at the core of the plot involves alchemy, history, and genetics (Harkness knows her stuff), and the hero and heroine were refreshingly honest with each other (impressive, given all the secrets everyone is keeping). Harkness even managed to avoid Mary Sue territory, despite the fact that her heroine has dead parents, incredible professional success, unusual hair and eye color, and super-unusual and -powerful magic.
The novel isn't perfect -- I'd have preferred a little more ancient mystery and a little less romance, and I don't know why male vampires must be The Boss of Everything -- but I've already picked up the second volume of the trilogy (natch) from the library.