This is a fairly standard Banks' sci-fi novel, which is another way of saying that it is wildly inventive, smart, enjoyable, and engrossing. Banks has a wonderful ability to create completely enchanting worlds, such that after reading there is this drop or context switch where you have to reload the actual world and how it works. This is a really high mark of quality, and something that I almost never find now that I'm a terribly jaded and sophisticated reader. So, go Banks! :) :D :P
In more detail: The book is not set in the main Culture universe, but it does share many similar themes and ideas. There are multiple levels of simulation/reality and pondering on their worth, there are AI's and AI haters, there are deceptions and clue hunting journeys to exotic locals, there are Azad like empires of varying degrees of cruelty, there are space battles, and there is a technologically superior, affable, intelligent and more life-seeking Culture like grouping. In addition, since this universe doesn't have the widely available FTL travel of the Culture novels, there are a lot of neat ideas about how buildable (and destroyable) wormholes that can only be moved at slower than light speeds would play out on a galactic scale. In addition to these higher level ideas, there is a continual stream of invention and detail in the various races, histories, locations, characters, and religions. Really, there is an embarrassment of ideas in here, and any one of them could have been the foundation for another author's entire novel. This is actually what drew me back to the novel; I had first read the Algebraist years ago, and wanted to refresh my memory of one of the religions in the book. (The religion is a variant of Nick Bostrom's Simulation Argument). I had meant to just find a few passages about the religion, but ended up consuming the entire book. The story moved much faster than I remember (or maybe the Atwood has re-calibrated my idea of what a slow novel is like?), and I think I enjoyed the Algebraist even more the second time around.