I have had a number of books to first learn field theory, then work through and develop models and then apply to investigatory work in theoretical physics in the capacity of a researcher, but I have never had a book like this before. I would rate it excellent, just like the famous and my all-time fave books on QFT by Itzykson and Zuber (the advanced account) and Peskin & Schroeder (a good student resource). It is a delight to know this book and to be enchanted by its charisma. It may seem difficult to a person having a quick exhaustive look (as Kaku does not elucidate much reasonings and detailed calculations at many places), but if you go through it, the lucid, illustrative and pedagogical style of Kaku is not difficult to follow. The book is suited to students of theoretical physics, particularly from the particle physics and condensed matter disciplines, but is optimised for advanced users as well. Kaku starts with introduction to field theory basics and then takes you through the actual intricacies of the theory and its methods in his well-known intuitive way, concluding with some impeccable sections on the modern concepts of Supersymmetry and Superstrings, quantum gravity and monopoles, etc, some of the best accounts I have gone through, so far. Great book!