I say it's wonderful, and it is, but I found it very tough sledding. Stephenson's writing is dense and discursive. Paragraphs and sentences are long, the type and margins are small. And the words are often spelled funny. And the page count is over 800. And I kept wishing I knew more late 17th century world history, because Stephenson knows it cold.
Highly recommended. I especially liked the "Trial by Crocodile" Jack undergoes around page 608.