I read the book and saw most of the PBS version. I think Brian Greene has done as good a job as can be done in bringing these complex ideas to the general public. I used to work in a string-theory related area, so I have an advantage when I read him over most people. My main complaint is that Greene doesn't emphasize enough how speculative all this stuff is. There are no experimental confirmations of string theory as yet. The other point I would make is that there's really a lot of stuff you need to understand BEFORE you try to tackle string theory, for example: Quantum mechanics The Standard Model
One of the downfalls of String Theory is that it totally fails to answer the fundamental question, How long is a piece of string?