Oh, what to think? Fascinating, confusing, difficult, easy, questionable. This book is brilliant how simply it explains some ‘basic’ concepts of physics (quantum mechanics, general relativity, Newtonian gravity, and so on,) going them over and over again through metaphors to make sure one will stick and explain to you what is said, but then again, it’s a book about (super)string theory which many physicists have criticized and rejected.
Maybe I should answer the question if I learned anything instead of focusing on if the subject is wrong or right as I have no qualifications to say either way? The answer is yes. Brian Greene’s recount of general relativity, what is known about black holes, about string theory was thorough and clear, but at times, I have to confess, confusing and going over my head. There were times I wished that he would have tossed out all the history and who did what and when and just give me the gist so I wouldn’t get lost in the dates, names, and times, but I know names matter (at least in this egoistic world we live in.) I understand why string theory still holds its gravity, and that is because of the need to combine gravitation with quantum mechanics, and if the thought of strings, makes this possible the appeal is great. And there is the thought of one unifying theory which explains the entire universe who wouldn’t want that (I know several who don’t, finding reductionism dangerous and wrong,) but it can’t come with the price of tested data and functionality. Then there is the curiosity of eleven dimensions and the possibilities they bring, which I didn’t quite understand.
Should you read the book? Yes and no. It’s an interesting curiosity, well-written (at times, when the writer wants to be clear of some concept, but not when he gets lost in the name jungle or tiny details apartment,) and goes over a subject which has been greatly funded. So, I would say it’s an important subject to understand.