Guide to the Crystal Gems

I have no idea who this book was written for. If you've seen the show, you already know all that's in the book, and if you haven't, there isn't enough info for it to not be confusing? Maybe some people couldn't keep up during season 1? Maybe it was written to fill in the gap cause of the hiatus between S1 and S2?

Anyway it is obvious that season 1 and 2 had a very different concept for the Crystal Gems as a Resistance movement (also very clear in the book), and I personally feel, the direction of the show changed after that.
Now I want to rewatch season 2.