As a guide to the vampire legend in folklore, and the history of some real-life "vampires" then I recommend this as a good starting-point. I found it very readable, and it was refreshing that he didn't seem remotely impressed by people who try to claim to be immortal blood-drinkers, which meant that the book wasn't clogged up with fantasists trying desperately to impress us that they're "different" somehow. The people who do claim to be mortal blood-drinkers are handled with sensitivity and restraint, and their case-histories make for fascinating reading.
The author cuts through all the tosh that has grown up around the vampire legend in recent decades, thanks to Hollywood, Anne Rice etc, and makes it clear that the original vampires of ancient folklore were not suave aristocrats in capes, but grotesque graveyard ghouls. He highlights how there are vampire legends in ancient folklore from all over the world, and describes some of the more famous historical "vampires", such as Vlad the Impaler and Elizabeth Bathory. Unfortunately he doesn't go into much detailed analysis of these people, but there are other books on the market for readers who want to go into that further (I can recommend any of Colin Wilson's true crime books). I will take exception to him including Haigh, the British acid-bath murderer of the 1940s, in amongst the historical vampires. It is largely accepted that Haigh only bragged about drinking his victims' blood to try and escape the hangman on an insanity plea. (It didn't work).
The book is rounded off with a section on psychic vampires, people who, either deliberately or unintentionally, drain other people's emotional energy. This is a fascinating area, as I think most of us have come across people like that at some time or another. The author though tries to tie it in with the common phenomenon of sleep paralysis, and the night hag visitations, and I didn't find this terribly convincing. Nevertheless, this book is highly recommended for anyone interested in the vampire legend.