His "Night's Dawn" trilogy (The Reality Dysfunction, The Neutronium Alchemist, The Naked God) that's his highest accomplishment. It blends what can only be called a 'fantasy' element into hard SF so plausibly that one only notices the fact that it's a distinct departure from the usual SF fare after the fact. After reading it, one will inevitably end up reading the short story collection "A Second Chance At Eden" (which includes an SF detective story that introduces the Universe in which "Night's Dawn" takes place) just to inhabit that Universe a little while longer.I read the Reality Disfunction. I did not think it was an especially good book and so I stopped reading the series. I did not find the fantasy elements to be either plausible or un-noticeable. Instead I found them to be intrusive and unbelieveable. I found the science fiction aspects of space travel and technology to be adequate and even interesting, but the entire arc plot left me flat.
Humankind is basically split into two groups in the future:
The Adamists are typical space opera humans. They have normal human vices. They fly around in mechanical ships and they make a lot of use of computers and cybernetics. Adamist colonies run the cultural and technological gamut from low tech by choice to very high tech to taking whatever they can get. Its all pretty normal except for a few cultural notes.
Which notes? Well among other things the entire Christian religion has reunified under the pope. This is a major plot point threaded through the entire work. One major character is a drunken priest. Gee that's not stereotypical or anything. At one point another character questions someone's salvation. Then he has wild promiscuous sex with her.
The Edenists are utopian biotechnologists. They fly around in living ships, live on living space stations, and are genetically engineered with a form of telepathy allows them to communicate with other Edenists and sentient Edenist equipment. When they die their telepathy allows them to transfer their consciousness into their space stations Overmind giving them a level of immortality.
Edenist society is darn near perfect. Oh there is the occassional jealous tiff, but as a rule they have no crime or vices to speak of. How did they accomplish this? Well knowing that they are essentially immortal made all those bad things just up and disappear. Yeah that makes sense.
My major problem is that the dichotomy here is completely artificial. Edenist tech exists and it is demonstrably superior to Adamist tech in every way. While it is understandable for Adamists to be squeamish about the whole Overmind hereafter, fundamentally the book makes it clear that Edenist tech isn't inextricably tied to Edenist culture. So why aren't Adamists making use of the acceptable parts? No answer. Plus, the two groups have been around for generations at this point and they are not completely isolated from each other. There should be some mixing of ideas but there isn't.
There are also lots of little annoying details. There are two types of living ships, Voidhawks and the larger Blackhawks. The main difference (other than shape) is that the Blackhawk can FTL jump significantly farther. The problem is that there is no advantage to this. Voidhawks can just jump twice in succession and accomplish the same thing in the same amount of time. So why would you ever bother with a Blackhawk in the first place? Beats me.
And none of this is getting into the arc plot which basicly has satanist criminals exiled to a colony world opening a portal to hell with the accidental help of an alien slug's exploring ghost.
There were just too many screwed up things in the story and the background and everything else for me to establish suspension of disbelief. Sorry.