Well, that was a rush. Just finished the book 5 minutes ago. I rate it 5 stars+ for sheer force of imagination, and 4 stars for characterisation, which gets slightly overwhelmed by the huge scope of the concepts in the book.

I had not heard of Neal Stephenson until I was looking for recommendations for books that would wean me off my commitment to Iain (M) Banks and David Mitchell. I was not entirely sure I knew what 'steampunk' meant, and I had not yet encountered what was described as 'hard' science fiction. I am not sure if I am any the wiser now.

The great things about this book are the strong female protagonist, imaginative yet coherent 'alternative universe' dystopia, and some decent science. The later parts of the primer involving Turing Machines are especially good. The whole story is really about a programmer writing a programme that will then be able to run and write its own programme on itself - thus transcending the Turing machine paradox. The mechanical rods and drums of the Turing machine are replaced by networks of humans, child development, cultural peculiarities and, most strangely, mass orgies. I cannot explain it better than that.

But it has a plucky heroine, some great action, page-turning suspense, heart-breaking drama (verging on melodrama - which is one of Stephenson's weaknesses) and is quite funny in places. The idea that British stiff upper lip and emotional coolness will have become the dominant cultural force in the world is especially encouraging. It's nice to read science fiction that does not assume we all become American. In this story, to be successful you need to be Victorian or Confucian.