This book is well researched, but it also got very repetitive. I think it would have been better if there were fewer monsters, with only the more memorable included. For example, there were multiple Nazis with profiles, their crimes, though horrendous, felt like repetitive facts. They could have been grouped together. The side notes and extra/bonus facts after each monster were probably my favorite. If you love history and like learning bits and pieces, this book is great for that. You can pick it up and put it down as you go without feeling like you're losing a story or something. We actually paced ourselves through this and found that it was better to try and retain more of the information we were learning.