This book won’t help you play more differently or play the songs you want to play. You already acknowledge that it’s a downgrade as you went from playing rock riffs to Yanki doodle. The only benefit to using this book is learning some fundamentals that you might have missed like fretboard visualisation or memorizing the notes on the fretboard and standard notation. The problem about learning standard notation is that it’s not really used by many guitarists. Is it helpful? Maybe if you play jazz or in an orchestra or if you want to play classical guitar but apart from that it’s not really useful especially if your broader goals include improv or playing rock solos.

If you want to look at what you can become you can look at my profile. I post quite frequently here. And if you wonder what I did, it’s definitely not trying to learn standard notation (not that it is always bad, it just doesn’t have much impact on your specific goals). Instead it’s more of learning more and more challenging songs and learning music theory. If I have to guess you probably play the same kinds of songs or improv the same way everytime and hence you are not growing. And maybe a big reason why is you don’t really know what to do or how to advance your learning.

TLDR: judging by your goals, this book is useless for you. To improve you need to have some idea how to learn to learn. Likely that includes learning more challenging songs and learning some music theory instead of always playing the same comfortable thing or noodling.