Harder sci-fi than usual, and hence a pleasant surprise to me after not reading any Brin for about ten years. He still can't resist the occasional puerile joke (The 'Fey-Beck' building?!) but I really appreciated the hard sci-fi approach to human speciation and the silentium universi. Also, there were a few very intriguing concepts and events left unexplained at the end that I hope turn up in future novels.

(view spoiler)[Weirdly, Existence was like a novel and a half: a whole novel-length story is told at a decent pace over as many pages as would be normal for a nice thick novel, and then enough material for a sequel - or two sequels - is sketched in over about half as many pages again. This did give a good sense of acceleration into a bizarre future without blowing our minds too much trying to describe it all, but it was a lurch. (hide spoiler)]

Is good. I read it on the Kindle so did not have any of the problems reported by some people below about the size of the text and the book.