Fly to Icarus,
Angel of the Asteroids.
The Spider sent you.
Listen, first off, you should stop what you're doing & go read Blindsight, if you haven't already. This is the follow-up volume to that-- I wouldn't say sequel, since reading Blindsight isn't required for this book to make sense-- & the hits just keep on coming. I don't have a lot of complicated thoughts to say about it, this time. This is really solid hard SF, with Watt's unique brand of grit. I like to call myself an "optimistic nihilist" & you could probably call him a "pessimistic nihilist" & not be too far off. It isn't that black & white, it isn't that stark, so I don't mean that in a reductive sense, just a descriptive one. Heck, if you read what I said at Tor.com about the Rifter series (which starts with Starfish), then you know what I mean. Actually, I think this book could best be described as a synthesis between the two series; the threat of βehemoth very much informs the dangers of Portia (using proper nouns means it isn't a spoiler, since by the time that comment will make sense to you, you'll know as much as I do). Ultimately, like The Rifter books, it is a story of the big dangers of small things, & Blindsight, this is the story of, to use Watt's own words slightly out of context, "a Darwinian fossil in a Lamarckian age."
So to give you the short version, Echopraxia is a story of a human man on the cusp of a post-human world. A trope of a lot of cyberpunk fiction is contrived "otherness"-- you know, think of Shadowrun & losing "Essence" as you get cybernetic implants. I think it is just technophobia, manifesting in weird ways-- see also, "magic versus technology" as the default in a lot of fantasy-- but Watts is a different matter. The post-human "people" of the book range from human, to near-human, to post-human, to in-human & ab-human. That's a lot of prefixes, but that's the range we get; the real post-humans? Aren't "people," not really. & the vampire? Calling her a "person," that's pretty silly. That doesn't mean they aren't characters. Valerie the Vampire we mostly see in reflection, ironically, as characters react to her, theorize as to her motives. She is a lacunae, left to the reader to fill by piecing together the plot...& she's probably my favorite bit of the whole book. You know me, I can't get enough of that sort of stuff. This is Watt's "big idea" book. You could say it is about "God" the same way that 2001: a Space Odyssey & Galactus are about "God."