Knowing absolutely nothing about quantum electrodynamics (the theory of photon interaction with matter), one can still make sense of the the book - and that is Feynman's true genius, in a way.
In a nutshell, QED is (at present) the nearest step to a Grand Unified Theory, the utopian theory which will explain the universe in the form of formulae that are so short that they can be inscribed on your shirt. It explains almost everything that we notice in our day-to-day lives - ranging from why you see your image in a mirror, to more esoteric effects such as predicting which particles arise during extremely high-energy collisions (such as in the Large Hadron Collider).
It is a marvel to witness a genius at work. Without any Math whatsoever, Feynman explains the theory while not leaving out any detail - where it works, where it doesn't work, and how our understanding of Physics is still pitiful, because every answer that we find brings a whole lot of questions to the fore.
The fourth chapter is on our understanding of Physics so far, and where QED fits in - it is a tonal mess, especially when compared to the succinct previous chapters, and it is the only time I felt disgruntled when reading the book.
TL;DR - an amazing read to reinvigorate interest in Physics/science, or to ignite the spark of interest that was never there in the first place. Either way, it is a must-read for the inquisitive mind. ( )

Another great Feynman book. Every time I read something by him, I get re-excited about physics. ( )

Okay, it’s been a while since I’ve read any science related books and even longer since I was in grad school. And Feynman’s excellent discussion of QED was a bit of a challenge but well worth the effort to remind us of “how it all works”. ( )

Mr. Feynman does a nice job explaining complex topic in simple terms so that person can follow his lecture on the nature of light and matter at the atomic level. ( )

As Dr. Feynman said, "Why are you going to sit here all this time, when you won't be able to understand wheat I am going to say? It is my task to convince you NOT to turn away because you don't understand it. You see, my physics students don't understand it either. That is because I don't understand it. NOBODY DOES." (Emphasis added)

And that about sums it up. After a few futile attempts to read and understand what professor Feynman was saying, I finally just read it as though I was attending his lecture while sitting in the back row. Whatever fragments I picked up helped me fill in the gaps to my heretofore fragmented understanding of the subject. I learned some names, some theoretical ideas, and some vague notion as to how this might someday all fit together. And then I walked out of the lecture (put the book down) shaking my head and made myself a gin & tonic to celebrate the occasion.

Thank you Dr. Feynman! Four stars for the effort! ( )