Qualitative, descriptive books on physics, I think, are often unsatisfying because nothing suffices like actually doing the math to appreciate the full impact and enjoyement of what physics has to offer. Yet this hasn't prevented the likes of Einstein, Hawking, Feynman, et al, from attempting to do so. Perhaps for the professional physicist such works are interesting by virtue of their historical content, but the lay reader will likely find such works wordy and boring. This book by Heisenberg transcends this milieu however, with the author's shear brilliance and eloquence an admirable spectacle in and of itself. Heisenberg is a terribly smart fellow and that comes through thoughtfully.
This book reads like a collection of essays and, perforce, some chapters could probably be left unread without great harm. Chapter 7, 'the theory of relativity,' being a case in point. No, the real beauty of this book is not in its trenchant reflections on the mechanical behavior of matter, but more on its correlation with physics as a human endeavor, and the evolution of human thought in philosophical terms, as well as language and how it expresses ideas; these themes, philosphy and language, are artfully crafted and make this book significant, not the fact that we can make atom bombs or postulate a universe.
Heisenberg emphasizes the Copenhagen interpretation, which states that the observer effects the outcome of an experiment by the very act of having observed the experiment. This is of course true primarily in terms of atomic physics and not of macro events. For example, if you try to observe an electron you will have to use high energy equipment to do so, which will effect the behavior of the electron. On the other hand, if you observe a sparrow at 100 yards with a pair of binoculars you're not really going to effect the sparrow. By observing it with binoculars you won't break its neck, which is the equivalent of what happens when you observe an electron with x-rays. The idea however, that the observer, or participant, does inject a huge influence by simply participating is significant on a macro scale in linguistic terms; a notion Heisenberg effectively sets out in chapter 10, 'language and reality in modern physics.'
The varying contexts and extensive meanings of concepts and language can and do effect the outcomes of human interactions in myriads of unpredictable ways. Perhaps at a time in humanity's past we could consider language as a logical system where a person either knew what they were talking about or didn't, or was lying or telling the truth based on what they said; a no BS kind of world where wise men judged the testimony of others in courts of reason, much like what occured in witchcraft trials, or in the way the Catholic church judged Galileo for teaching Copernican ideology. We know better now days, and this is, I believe, why Heisenberg makes such a point of the Copenhagen interpretation; not to show that it applies to macro physics, but rather to show how it applies to language and psychology. It's a tough analogy but Heisenberg makes a remarkable effort that engenders contemplation and awe. After all, we still have wise men judging the testimony of others in courts of reason, a sobering thought. This stress on linguistics may seem insignificant today but was probably more germane to the time this book was written, in 1958.
If you like physics, philosophy, and psychology, not necessarily in that order, you'll probably like this book. Chapters 4 and 5 alone, the two chapters that track the birth of quantum physics philosophically, make the price of this book a worthwhile investment.