Revelation Space by Alastair Reynolds
When I began reading Revelation Space, I was impressed by the way Reynolds was able to portray the universe he was creating. The fact this was his first novel added to that. After a while, I started to view the story lines in the various subplots as seeming to tell us about events we didn't really need to know about - or at least not at that level of detail. That's not necessarily a bad thing. An "unnecessary" sequence early in the plot can give the author an opportunity to mention in passing details that provide background about this particular universe, before one gets to the "essential" plot when the reader needs to have his bearings.
Then as events developed, the subplots started showing more signs of wheels within wheels and other convolutions. The plot becomes something like an espionage / mystery story. The reader is kept wondering: Who actually doesn't have an underlying agenda? Who is an "agent" for this or that group, and who is a "double agent"? What are the underlying agendas? And so on.
The book takes place centuries in the future. The human race has diverged to some degree based on the extent of neural implants and other augmentation used by certain groups. While there isn't a galactic civilization of various species, there are other beings in one sense or another. There are "Jugglers" - organic neural systems in the oceans of some planets that can change humans who go into those oceans. There are "Shrouders" - an artificial area in space which keeps people out - except for one man who claims an old intelligent race has taken and isolated potentially dangerous technologies from worlds around the galaxy.
Some humans travel between the stars. They use spaceships that travel very close to the speed of light, but not faster. The ones we get to know are ruthless traders - who don't seem to do that much commercial trading. They do have quite a collection of immense weapons. And they have a captain being kept in cryogenic storage to slow down a "plague" organism transforming his body.
On the planet Yellowstone, a mysterious woman hires an ex-soldier to kill a man in another star system. (In another subplot, we're introduced to the intended target as an archeologist working to understand a dead alien culture on an obscure planet.) To get to him, the ex-soldier arranges to become a crew member on the traders' huge spaceship going to that planet. The traders are going to get the archeologist. The only scientist who may be able to help the captain is the archeologist's father. The father is dead, but an AI version of him remains, which can be put into the archeologist's head to operate on the captain. The archeologist is being held prisoner by a group that has overthrown the government, but is not yet in complete control of the planet. The ex-soldier has been taken on as the ship's gunnery operator - to replace someone who went insane babbling about Sun Stealer. And Sun Stealer seems to be the name of a deity of the alien culture the archeologist has been studying…
The book is well written and the story kept me interested, but this type of plot may not appeal to all readers.