I enjoyed this book for a few reasons. 
I liked how the author was able to be honest about being a complete monster in his past, prior to being sober. It was interesting hearing his reasons for being so horrible to his past partners. It made me think about things I have done similarly (not to the extent the psycho has) but also what others might be doing to people in relationships. 
The whole idea of playing games with someone to this level was intense. 
I enjoyed reading about how Holden decided to get sober and try and become better from what he was in his past. 
Reading about his experience being on the receiving end of the manipulation and games was hard, familiar, but also real in a way. As much as I was glad he was getting a taste of his own medicine I felt bad for him, but knew he deserved it. I was captured by the pain he was feeling and very quickly reminded that he is a complete piece of shit and deserves to feel horrible. 
Is redemption possible? Sure. Can someone’s past have an affect on the way people perceive them moving forward? Absolutely.
Overall, it was a good read and I would highly recommend it. Truly makes you stop and think about how you might have/ do treat others in relationships, and also about how much we as individuals are willing to put up with, out of “love”.