This is primarily a biography of Einstein, with a focus on his reluctance late in life to accept quantum mechanics. Bodanis describes his early successes; his decision to compromise his general relativity equation with a "cosmological constant" in the face of contemporary evidence; his regret and disavowal of the cosmological constant when the astronomical evidence changed; and his decision never again to allow contemporary evidence to sway him against his scientific instincts, resulting in his increasing isolation as the predictive power of quantum mechanics swept his friends and colleagues in a new direction.
Einstein's struggle with the cosmological constant was driven by a concern with mathematical elegance, but his struggle with quantum mechanics was motivated by his faith that the universe was ultimately rational and predictable. In this sense, Bodonis' book provides an excellent counterbalance to Lee Smolin's "Einstein's Unfinished Revolution."
The presentation of ideas in physics is greatly simplified. For example, the general relativity equation is expressed as "G=T". Bodonis provides an appendix with slightly more detail, as well as a link to a web site with more explanations and illustrations.
This is a highly readable and informative biography, with many entertaining and touching anecdotes about Einstein, his professional contemporaries, and his friends and lovers, along with a useful presentation of the ideas in physics that framed his life.