This book along with the first volume are the only books that I found to give in-depth coverage aimed specifically at NLHE Cash Games. The biggest thing going for the books is that they're thorough. Around 800 pages of strategy, quizzes, examples, and some light mathematical explanations. Thankfully, not a page wasted on teaching you how to play. Even the English is quite good! (Most poker books are near unreadable.) I reread this before every game to tighten up and remind me to be aggressive and I've certainly improved. I actually ENJOY reading it, too.
The only downside might be that the examples seem sometimes inconsistent, such as recommending a raise 80% of the time in one situation and 70% in another where it seems the recommendations should be reversed, though who am I to judge? Harrington's playing style is very tight and very loose players might find too few recommendations on how to act in situations with poor hands.
Neither of the above gripes is enough to knock these books down from a 5-star review. In short, you'll enjoy reading this book and play better afterward. Definitely get the first volume, too.