An excellent surprise of a book. The author has written this book as a layman survey of the Euler formula for the special case where x = pi, e^i*pi + 1 = 0, but eventually expands it to the general form of e^i*thera = cos theta + i*sin theta, and makes fairly elementary, but intricate, demonstrations like DeMoivres relation, with a brief interlude into finite series, then finally constructs the relation using a LHS, RHS argument with a finite series expansion of cos theta and sin theta, I *think* using DeMoivres relation.
Though the above is the roadmap to the "destination", the true value of the book is the insightful commentary the author has peppered between the simple mathematical construction, on a range of topics like the nature of elegance in math, discussion on abstraction and concreteness in math, and how the mathematical literati which value the former helps retard the advancement of general mathematical education for the public, skewing the subject to an esoterica appreciated by a few, instead of a joint human activity for all, historical tidbits on Leibniz, Wessel (who was the first to visualize the Euler formula as a spherical coordinate), and Euler himself, and gives the reader a glimpse of the multitude of applications Euler's formula has made possible in engineering. There should have been something on Fourier transform, that application alone has touched probably every field of computing, engineering, science, and even parts of social science. Nothing on that, or the associated notion of convolutions, another deep construct enabled ultimately by the Eurler relation.
The biggest miss in this domain, and should be included in version 2 of the book is the Bloch Sphere construct in QM. Given the Born interpretation of the square of the parameters of the ket-states of a superposition, one can normalize these series of square parameters to equal 1, and thus map them into a spherical coordinate system, using the Euler relation. Thus, constructing properties of states of qubits by contextualizing them as rotations across 2 axes.
This application of Euler's formula may be the most profound and impactful yet of all applications in the history of science. There are many other applications of the formula which could triple or quadruple the page count. As I was reading the book I believe that the layman may realize that although they may start off viewing Euler's formula similarly as other famous equations, like E=MC2, as the author demonstrates, this isn't true. Whereas the former is a sort of deep discovered fact about nature, Euler's formula is more of a swiss army knife that allows one to generate facts about nature. If the general readers come away with that sort of insight, the book has definitely done its job of expanding minds.
To students of math or pros, I think this books commentary on the subject and history is sufficient and keen enough to justify a reading, especially for those who may be dusting off their mathematical chops after a few years of atrophy from non-use. A great book all around, recommended