Fantastic text. If I had to recommend a single resource from which to really learn string theory, this would be it. Its treatment of string geometry and flux compactifications is particularly good. If I had one complaint, it goes a little fast with some of the early material doing a bit of hand waving around questions such as critical dimensionality and zero-point energies (Polchinski Ch 2, 3, and 10 fill in these details nicely). Overall, I strongly recommend this book.