This Quantum Field Theory text stands apart from others in so many ways that it's difficult to list them all :-). A very unique QFT introductory text.
One problem with learning QFT is that it is so easy to get lost in the mathematical details that the core physics concepts often get obscured.
In my opinion, Tony Zee overcomes this particular problem quite successfully. He keeps algebra to a bare minimum, and tries to find the shortest route to the physics ideas. He chooses examples that illustrate concepts in the fastest possible way.
The chapters are short. So refreshing! Each chapter has one or two core ideas. You can go through one in ten minutes (glossing over the math), and then you go back and do the math.
Part I (first eighty or so pages) is called "Motivation and Foundation" and is a rapid introduction to QFT. It is also a summary and sweeping overview --- introducing path integrals and Feynman diagrams and making a very intuitive transition from Quantum mechanics to Field theory.
The next three parts cover spin-1/2 particles (Dirac spinors), renormalization, and symmetry (breaking), standard fare for QFT texts. A sampling of condensed-matter applications is given in Parts V & VI, and then current high-energy topics are treated in parts VII & VIII.
The applications make this text stand out. There is a selection of advanced current topics like the quantum hall physics, surface growth, string theory, D-branes and quantum garavity, not usually found in introductory field theory texts. Of course none of these topics can be done justice in a book at this level, but getting a taste of advanced issues is a great treat.
The exposition is breezy and chatty, as the author admits was his intention. The text is never boring to read, and is at times very, very funny. Puns and jokes abound, as do anecdotes involving the inventors of QFT.
Renormalization is discussed through a lively dialog between student Confusio, a female Smart Experimentalist (SE), and a senior (Egghead) theorist. Ode to Galileo! Section headings alternate between serious and hilarious --- one section is called "Wisdom of the son-in-law". The path integral formulation of quantum mechanics comes out of a conversation between a teacher and a "wise-guy" student, who happens to be Feynman.
And so on and so forth.
The net result is a book which is much easier, and more fun, to read than any of the other common QFT books out there. Tony Zee's skills as a popular physics writer have been used to excellent effect in writing this textbook.
One more distinctive feature is that there is equal emphasis on condensed-matter and high-energy applications. Most QFT texts today, unfortunately, are so biased toward particle-physics that they tend to put off condensed-matter students. A. Zee has broken the mold!
Is the treatment "over"-simplified? Maybe simplified, but not dumbed-down. The high concept-to-pain ratio certainly seems worth the simplification.
Is this text only good as a supplement? Well, it is after all a "Nutshell", so maybe other texts are better for details. But as an introduction to QFT concepts, few other books match this.