A strong effort, although not one of Reed's best and seems to lose a lot of momentum in the middle. Very strong opening and close, however, and the main premise sustains itself for a lot of neat idea-centered story. The whole question of humanity's symbiotic relationship with an alien species is well conveyed here, and serves as a slow revelation to how alien and potentially menacing the 'normal' humans are. What also works here is the sense of scale, the sheer numbers involved with the wider galactic civilization and then the degree of mental power hinted at with the aliens and made explicit in the end. Much of science fiction gestures at huge expanse, particularly in space opera, but tends to go with a lot more small scale circumstances to ground the narrative in the conventional. Reed works with a similar balance generally, but seems to have a lot more awareness of the sheer numbers that would be involved with reaching into space, and in turn how that changes the whole quality of society and any narratives formed from it. There's a tone to that which I find irresistible in virtually all of his books, a linking of story and setting that pays off quite well. On one level this book like most of his is a very conventional, classic piece of SF, but there's an energy to investing the premise and focus on coherence that make this work worthy of notice. It doesn't transcend a stock premise in the way that a lot of the best science fiction writers do (see Richard Morgan, for instance) but it invests in and fulfills his setup in a way that feels relatively rare. There's something about that which makes Reed's futures seem uniquely real, and the larger strength of the author is in making his works fairly detailed in tone and scale.
Among other things Reed may be lowering my opinion of Stephen Baxter, since he shows an enormous commitment to wide-scale futures without sacrificing character and politics in the way that Baxter does most of the time.
Better than: Swiftly by Adam Roberts
Worse than: Marrow by Robert Reed