I've read most of Stephenson's work (still haven't gotten to
Anathem, and I never could get past the first few pages of
The Big U). I agree with the following:
That is basically Stephenson in a nutshell — Long, sometimes ponderous, exposition leading up frenetic action of worldly proportions.
And then they just end, rather than conclude.
The exception (among the books I've read) being the
Baroque Cycle - the ending is hardly the best part of the novels, but it is a proper ending, not just the "oh no! I've run out of book! And they all lived happily ever after!" feeling that I got from the others.