While I might disagree with the way some things are implemented or presented, it does not change the fact that this book is a very good introduction into event sourcing. If this book was framework agnostic its value and relevance in the years to come would be much higher.
Although it doesn't have all the necessary details to become a master in event sourcing, I believe it to be a good cookbook with useful examples. It also contains some useful side-reads (articles, books, etc.) that can be helpful.