Asher's Polity series are set a few hundred years in the future when humans have colonised many different worlds, with the help of teleportation devices called runcibles. There are lots of AIs - some run the runcibles, some run ships, some run cities, some run planets, they're pretty ubiquitous. And you can be linked into the network to interact directly with these AI (only as a government agent, I think) - which is called being gridlinked. As well as being space opera, I think of this book as having some of the same flavour as William Gibson's earlier stuff - only it's cyberpunk of the 2000s not cyberpunk of the 1980s.
It starts with something I always think of as a Stephen King trick (tho I'm sure lots of other writers use it) - you're in the head of someone & just getting to know them & their story and then they're dead. This is the set-up for the whole story, someone goes through a runcible and it goes wrong, the resulting release of energy is sufficient to blow up the runcible and most of the people on the planet and those who survive are frozen when the terraforming stops happening (it was being fuelled by waste heat from the runcible operations). Sabotage is suspected and one of the best Polity agents, Cormac, is called in to figure it out. As an added complication for him he's been gridlinked for 30 years and this has started to atrophy his ability to interact with and empathise with people. So his superiors not only call him in but also tell him he needs to deactivate his gridlinking before taking on the job (otherwise he can retire - I think it wasn't a threat as much as an acknowledgement that he wasn't fit for duty any more, his retirement wouldn't be a hardship, but he likes his job). As yet another complication he's managed to piss off someone in his last job, who turns out to be more than a little psychotic and follows him across the galaxy to kill him.
Like I said at the start, I enjoyed reading this although I did find the ending a bit hard to follow. I wasn't really sure what happened, but while writing this post I looked on wikipedia and found a link to an alternative version of the ending on Asher's website where it's more spelt out. Having read that I think I can see how all the clues were there, but I do think the original ending is too opaque - much better with a little more explanation.
I liked the way you get to see Cormac from the outside first, which shows how oddly he's coming over to normal people before you see inside his head. And I liked the way that once we're inside his head gridlinked-Cormac feels right for what it'd be like to have the internet (and more) in your head, for instance he looks at something and automatically looks up info on it. I wasn't sure I agreed about what the side-effects of being gridlinked for 30 years would be, but then the withdrawal difficulties that Cormac has made it feel right.
The science in the book was explained just enough for me to hang my suspension of disbelief on, but not enough that I started picking holes in it (of course, not being a physicist helps with this...). The little bits at the start of each chapter were neat - some gave you little bits of useful info about the world of the story and some added another layer to it. Like one tells you about Cormac's superior and it seems somewhat fantastical and they say he's probably legendary. But then another one tells you about Cormac and how he's a legend used to frighten potential Separatist terrorists into behaving ... and yet we know he's "real" coz we're in his head, so how much of the other stuff about his superior is also real? I can't remember much about later books, so I don't know how much of that we get to find out about.
So I'm keeping this one :) Might pick up some of the others, although perhaps not immediately (I know I want to get the rest of the Erikson series & we're behind on the Wheel of Time, so I think perhaps buying even more books right now is not the best idea!).