Interesting read but definitely not a page-turner. Euler was a genius on par with Leibniz, Newton, Descartes, etc. Few if anyone equaled his mathematical prowess during his lifetime and maybe for another 200 years, except for a few random geniuses here and there like the Bernoullis and D'alembert, etc. To give an idea of how prolific and advanced he was, he would be remembered today for Euler's number and work on logarithms alone. For five of his breakthroughs, logarithms and calculus of variations and a few others cumulatively, he'd be remembered as a giant of math. But he probably had 120 or so such discoveries. And he was totally blind for the last 20 years of his life.
Euler was alive when the war over who invented calculus was raging across Europe, Newton vs Leibniz. Back then scientists were natural philosophers by name, and they were carving out paths in mostly physics, math, biology, anatomy, etc. They were inventing entire fields left and right. Hydraulics, electrical engineering... countless fields and niches. Their skills were highly valued by royalty bc of the constant need to improve ballistics, engineering huge building projects or those using new technology, and harness nature's power for industry. Also, all the most powerful emperors and kings were personally very involved in building up universities and natural philosophy societies, and of course, were important patrons. So there is an interesting historical element to the book. Euler became very involved in administration in Berlin and a typical scene in the book would be Euler needing money or some sort of resource or even just an answer from the emperor, who at the moment was in some field tent fighting a war.
The best parts of the book are those discussing his work. Euler developed many notations we still use today, pi, i for imaginary numbers and "Euler's Number" e, which = 2.7818 but is irrational. Euler was in constant disputes with various philosophers, but at any given time maybe 1 to 3 people on the planet were able to fully understand his work. He was breaking new ground every time he moved his pencil. Solving Fermat theorems and ancient unsolved problems left and right. He took many of Newton and Leibniz's discoveries and developed new math to carry them further. For example, many mathematicians and Euler spent considerable time solving the vibrating string problem. This is remarkable considering how prolific and advanced wave mechanics are today. He was the master of differential equations, derivatives, integrals and various other types of calculus. He married physics to differential equations. And every now and then a young genius like the polish LaGrange and French D'alembert would pop up and the two would collaborate to push math theory, etc even further. 150 years before Einstein, Leibniz suggested that time and space were relative. And during Euler's time there was a heated debate over Monads, which was their idea of what we'd probably call an atom today. What was it, etc? They were developing early physics, both theory and thru experimentation. All these fields were so new that very respected individuals had very serious differences of opinion of fundamental ideas that would be the basis of various fields. They wanted to develop standards for their fields, find constant values and fundamental laws, etc but also for science itself. The scientific method is a good example.