For a book about a supposed genius psychopath, I see little evidence of the "genius" part. He was intelligent for sure, but plenty of people can claim that adjective without anything more. The most fascinating section of this book was actually at the end after Rulloff was executed - the discoveries made by the burgeoning neuroscience field. 

Perhaps I am less than impressed due to modern knowledge of so many different known figures (fictional and real) who were actual geniuses and psychopaths. At the time, I suppose it was harder to conceive of someone who could do such things and not also be a raving lunatic.