I wish I had read this in high school.
Of course, I couldn't because I left school 30 years before it was written.
The book covers space, time, spacetime, non-locality, relativity, unification, the second law and so much more.
The writing is clear, concise, easy to read and has a gusto and enthusiasm that reminded me of Carl Sagan.
Newtons Bucket is analysed in exquisite detail throughout the book as a kind of backdrop to how physics has changed and how the refinements and revolutions have been able to more and more accurately describe how (and why) the water spins and forms a concave surface.
(If you have no idea what I've just said, go read http://en.wikipedia.org/wiki/Bucket_argument)
The author has a mention in wikipedia: http://en.wikipedia.org/wiki/Brian_Greene and has even had an appearance on "The Big Bang Theory". Cool.
Even though the book is slightly out of date with respect to the LHC and later refinements to String and M-Theory, Loop Quantum Gravity et al, I strongly suggest that anyone who wants a thorough grounding in the current state of physics should go out and buy this modest little Penguin book.
I will be definitely getting his later work "The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos" as soon as I can.