Brilliant. But it's a Stephenson book, so I've come to expect that.
Less punch than Cryptonomicon, but it's also deeper and more thorough in its approach to worldbuilding. I wasn't convinced by what's eventually revealed to be the central premise of the book (it's a theory that I generally think is a load of hogwash), but I have no complaints about how it's stated.
ISBN 1843549158. Search for this book on Wikipedia or isbn.nu.