Easily one of the best non-fiction/historical books I've ever read. It took me a long time to finish the book because I'd read a section and then I'd spend some time studying the science behind the material. If you pay attention you should come away with a decent understanding of how (and why) the original bombs worked.

Rhodes doesn't shy away from the human and philosophical aspects of creating the bomb. In particular a fair amount of space is dedicated to the personal struggles of the scientists: they knew exactly what they were building and how their inventions would be used. If was fascinating to learn of the ways they were able to rationalize their choices.