I gave up on System of the World after it turned out not to be a trilogy after all. Anything else by Stephenson I obsess over, though. Anathem was basically a religious experience for me and I read it straight through twice - something I only do about once a decade.
This is an exciting thread for me because you folks are the first people I've talked to that didn't hate it, and I've been somewhat afraid to take it off my shelf.
I might be ready for a fourth reading now.