This is the second Greg Egan book I've read. The first was Permutation City and that was excellent and the first book in which the idea of copies/upload/personality constructs (PC) made some sort of sense. With Diaspora Egan goes well beyond that, 150 pages in its an excellent book. Even though written nearly a decade ago it visualisation of a future for humanity is far better than most modern SF authors, and it should be quoted as much as Snowcrash when it comes to talking about virtual worlds. The opening chapter describing the "birth" of a new PC, and that PC's first interaction with external data streams, and then its avatar and its virtual world home are superb.
For the record, and it doesn't include any spoilers, Diaspora identifies a future only 100 or so years out when humanity has post-signularity fragmented into about 4 different "species" (compare with the BT future evolution chart I posted a fortnight or so ago):
- Statics - organic, unmodified humans (i.e. us)
- Exhuberants - organic modified humans, whose modifications range from cosmetic to the extremes to cope with hostile environments such as the sea and space
- Gleisner robots - "uploaded" and (I assume) digitally evolved humans who live in mechanical bodies
- Polis residents (I don't think he gives them a name as the story is from their point of view) - uploaded and digitally evolved humans who live in virtual worlds (although those worlds have feeds of the physical world, have agency in it through robots, and can step out into it through Gleisner robots.