In the process of working through this book but I already have some thoughts.
I'm grateful that there is a book with such a comprehensive analysis of middlegame ideas. As Nunn himself points out, middlegames are often nebulous and difficult to analyze, so having a book which attempts that is commendable in and of itself.
That being said, what I've seen of the book so far has been a real mixed bag. Some of the sections have good explanations about specific situations and offer general points that can be applied across different scenarios. However, other sections feel as though Nunn is trying to show off how great his analysis is compared to other masters without clearly discussing the "why". I understand that analyzing games and deducing alternate moves is important to developing tactics and strategy, but there really needs to be basic principles which are reinforced by the analyses.
For instance, there is a section titled "Creating a Plan" which I assumed would discuss concepts of developing and implementing a plan once you're out of the early game. (This was of particular interest to me because I'm at a point in my play where I need to work on my middlegame.) Instead of any kind of guidelines or concepts, the two-page section was just analysis of a pair of games with little to no clear discussion of the players' plans.
This makes me wonder what the target audience is for this book. Is it intermediate and advanced players? Can beginners get anything out of this? Is this what the accepted method of learning chess looks like, just analyzing moves within games without clear explanations as to why those moves matter?
I bought the book so I will endeavor to complete all the lessons, but I'm already feeling a bit let down by what I've seen. Perhaps it will pick up.