The first chapters focus exclusively on the SOLID design principles and best practices for testing and vendoring while the rest of the chapters get progressively more and more technical.

I think the material should be relatively easy to follow up to chapter 11 for anyone with a basic understanding of programming in Go. Chapter 12 is a bit more complex as it describes the implementation of a distributed graph processing system.

I would definitely recommend taking a look at the (heavily commented) code on GitHub to see for yourself.

Mastering Go from the same publisher might work better for you.