Gell-mann is, quite simply, an expert in more fields than most people have a passing interest in. Added to this is a lucid, entertaining writing style, and the ability to knit together seemingly disparate concepts from the fields of physics, cosmology, genetics, information theory, evolution, behavioural psychology, sociology...you name it.
It seems a few people have been criticising Gell-mann for overextending himself, boasting about his own achievements or simply writing a dislocated, jumbled book. My advice to these people is to 'look for the patterns behind the apparent randomness', as Gell-mann might have put it (because they are there, all right), give him his due for his own (considerable) contributions to physics and admire his courage in even attempting to connect so many ideas, let alone succeeding as well as does.
I loved this book, and I think anyone interested in just about any aspect of science ought to like it too.