An original, well-written, absorbing piece of sci-fi-fantasy. Half of it involves the setting of a feudal world, which drags a little, but, in its technologically-advanced ruling Aristoi society, is impressive, and, it is redolent of the pantheon of gods of Zelazny's Lord Of Light [1967], reflected in its Asiatic cultural dips, though it by and large borrows most from the Greek pantheon. For the aristoi are effectively gods.
Aside from its feudal setting in the latter half, its science fiction, its world-building, is credible and integral, without any attempt at scientific explanation of advanced technological physics, except in overall reference, such as the galactic communications system based on tachlines, which somehow deploy tachyons, we suppose - and that's it, no further attempt to explain. Similarly with their datastores, occupying whole moons - no attempt at trying the describe how data is stored. And a major theme: nano-technology.
I liked this. It set my imagination aflame - for I too have this concept of personality 'aspects' in my writing, but in a different way - my Limited Personalities are materialised either as clone-avatars or specifically as virtual Servitors. Same thing, different names. What Williams also does, to varying degrees of effectiveness, is to juxtapose the real personality's action and dialogue - Gabriel, e.g. - in a column alongside the daimones' dialogue (and limited activity, e.g. messaging). This is an intriguing device, but only partially effective, especially when such layout continues for spells longer than one page - it diffracts the storyline a little. This is only a minor frustration merely because you become so bound up in the story's action that you want to proceed apace in the timeline, and find occasionally you have to read a section that either overlaps and so anticipates or lags behind the main thrust of the action. A minor quibble; otherwise, a nice device.
But what Williams achieves - mostly, aside from a clutch of other minor quibbles - is a good fluent, rich, authentic and credible universe and read. He deploys lots of classical references - Chinese, Greek, Roman etc. - and a great deal of cultural reference - philosophy, poetry, plays, opera, music - and describes his luxuriant worlds with a rich style, if on occasion overdoing the floral embellishments of dress and place. Another minor quibble is his slight overuse of the luxuriant, sensual, often (too often by one episode) sexual world of the oneirochronon; but later on you realise why he added the one apparently excessive (Troika) scene.
So there are very few minor gripes with the book, including an essentially pointless epilogue, and after a couple of nights' reading, I wanted to finish it, and stayed up to do so. Now that's the sign not only of a good story, fascinating characters, a first-class lead, plus well-measured plot and action, but of a very good writer style-wise. Yes, you are impressed by Williams's 'smart' and his craft, and it is a very rich, sumptuously peopled work that puts it very close to the top draw of sci-fi, and certainly a contender for Zelazny's unique throne.