I think Stephenson does a great job creating interesting characters and worlds, and also does a good a job with setting up stories. What he struggles with is ending them - apart from the time he spent explaining the nuts and bolts of elementary crypto-theory what really jarred me was the way Cryptonomicon ended. Which was "abruptly" and "poorly".
I really enjoyed Snow Crash - which is something of guilty-pleasure pulp cyber-punk. I really really liked The Diamond Age - I think it his best book in some ways.
After Cryptonomicon I haven't been able to bring myself to start the Baroque Cycle even though they've been on my bookshelves for nearly a decade now.