In A Fire Upon the Deep we learn early on that our immediate cosmic neighborhood is divided into Zones, working outwards from the Galactic core. In each Zone, cognition and technology work better. So in the core it isn’t possible to be intelligent at all, in the Slow Zone it’s possible to be as intelligent as a human but no better and you can’t go faster than light, in the Beyond you can have FTL and anti-gravity and enhanced intelligences, and in the Transcend you can have godlike intelligences and Clarke’s Law tech. The novel takes place in the Beyond, with an excursion to the Slow Zone, and concerns a problem from the Low Transcend risking upsetting the whole thing. (Vinge apparently thought up this brilliant universe as a way around his idiotic Singularity non-problem, which just goes to show that a) constraints can produce excellent art and b) every cloud has a silver lining.)Most of you know Jo Walton. (One of you is Jo Walton.) This book of reviews originally published on Tor.com in 2008-2011 is an extended conversation about great (and some less great) works of SF, part of a chat that I've been having since the start of the century. The final essay, which I think didn't appear online, established the agenda: this is not literary criticism, this is talking about books, not new books but books that she has reread and thought about for our benefit.
As always, I find I have distinct points of convergence (Bujold, Le Guin, the Clarkes - Arthur C. and Susannah; Doorways in the Sand, When the Kissing Had To Stop) and divergence (Brust, Cherryh; to an extent Delany and Asimov); but enough of the former that I will be adding several of her recommendations to my own wish list (Random Acts of Senseless Violence, Black Wine, In The Wet).
And the piece on The Last Dangerous Visions is grim but funny at the same time. All good fun and recommended.