Several weeks ago, a co-worker loaned me this book. I wasn't initially certain that I wanted to read it, but I really enjoyed the experience!
I think one of my favorite parts of this book was the degree to which the author incorporated actual historical facts. For the most part, I felt like I was really just reading a work of historical fiction, which is one of my very favorite genres. I was totally fascinated by the concept that the nation was being torn apart by the existence of slavery. For some reason, in my education so far, I'd always had the impression that slavery was not a source of significant cultural tension but rather a pretext for war.
I don't believe the fictitious premise that one reason slave owners were so excited about protecting the institution of slavery was to ensure that there would always be access to victims. However, that prospect deals with an interesting logistical issue: how do vampires eat without being caught? I agree with the author that using slaves would be a relatively simple way to avoid detection, assuming the vampire can afford to buy them.
All in all, I would recommend this book. There is a little bit of gore, both when the vampires feed and when Abe Lincoln hunts (and kills) them. While there is quite a bit of fantasy, I think it still presents some cultural aspects that ring true.