Reddit reviews The Algebraist

Iain M Banks' has a book titled The Algebraist, there are aliens in it called Dwellers; each individual dweller lives for millions of years and the species has been around for 10 billion. Dwellers are...not what you'd expect from beings that old.

You remind me of the villain in The Algebraist...his name escapes me.

I've seen this before but it's still a fun read if you're familiar with Banks' Culture books. "Use of Weapons" and "Excession" are good places to start in the Culture universe.

Banks has a new book out, not in the Culture universe, that's quite good as well: The Algebraist.

Nobody has mentioned Iain M. Banks yet, so how about

The Algebraist

Excession

Against a Dark Background

Another military sci-fi novel with several unique twists would be Vernor Vinge's:
A Fire Upon the Deep


Hard to beat Ender's Game, though. Old Man's War is really good; Armor is good but kinda depressing.

I can think of lots more, reply if you'd like more suggestions :-)

Iain Banks wrote a nice fat novel where the galaxy's primary religion had the same idea.

I love the Culture books by Banks, but I think The Algebraist is the best sf he's written to date. And to my mind, no dull parts anywhere, middle or otherwise. (Okay, to put a very fine point on it, I did think the "villain" was little more than a cartoon but the rest of the book is just about perfect).