This is work of astonishing imagination and, being Stephenson, it is very well written. Unfortunately, it's all edifice and no substance. The characters are paper thin and there is no plot to speak of. It's a little like the extensive model train set in your neighbor's basement. You acknowledge the scope of its creation and admire the skill with which it was built but, at the end of the day, who cares?
The first 2/3 were great, the science everything a hard science-fiction reader could want. The last 1/3 required science as magic hand waving to allow for the premise, which although the premise is interesting, the suspension of disbelief it required borders on fantasy.
I wish Mr. Stephenson had wrapped it up after the first book. The manner in which the residents of Izzy were able to accomodate their new life and use all of the ingenuity and technology they had available was fascinating. The second part seemed more about using up all of his research so it wasn't a waste of time. I read to the end, but by then it was "I've made it 800 pages, I'm going to finish".
