My "favorite" part of The Diamond Age was when he had a whole scene solely so one character could explain to the reader what another's (lame) motivation had been for the last half the book or so, as it had been in no other way established or explained up 'till then and the book was about to wrap up.
Every time I read a Stephenson novel I have to break through that first quarter to a third before I'm fully taken in. It's like a dog or cat finding a comfortable position to sleep in. Snow Crash, The Diamond Age, Cryptonomicon, all require me to push through that first part before I can get comfortable.
I had tried (and failed) to read Crypto about 3 times before I finally broke through and realised his plotting wasn't bad, he just couldn't set it up right, or something.
I think it's because he hadn't learned a whole lot of bad pacing habits at that point, but had already developed a strong descriptive style. Snow Crash is an evolution of that. The pacing is a mess, but entertainingly so, and the first-class descriptive writing and dialogue makes up for it.
He desperately needs an iron-fisted editor in his life. It's a tragedy that he doesn't.