This is SF-realist high-tech space opera, of the type that Greg Egan and Iain M. Banks write -- which is obviously a wide range of writing. This example tilts heavily towards the Egan side, although the long technical digressions aren't quite as opaque and the characters aren't quite as stilted. If you're old enough to have a stereotype of "Analog Mafia SF", this is it.
The writing itself is quite bouncy and charming (unlike Egan!) and this drew me in at first. It's a multicultural galactic setting, high-tech but not post-scarcity, with lots and lots of very non-human aliens (described in loving detail). On the planet of No-Moon, a bunch of neo-Neanderthal traders and sentient-coral sailors become concerned about an incoming interstellar invasion force. Or rather, missionary fleet. Cosmic Unity is the nicest possible religion, based on principles of materialism and universal tolerance, so that's reassuring, right?
Sadly, this is all an excuse for an Idea Story about evolution and memes, which couldn't have been that groundbreaking even when the book was published (2004). That's spiced up with an Evil Repressive Fundamentalist Church Story -- which has not been groundbreaking since the first flush of genre fantasy in the 1970s.
(I'm not questioning whether Repressive Fundamentalist Churches can be Evil, good grief, no. I'm just saying that ripping aside the curtain and saying "Look! They're torturing people and saying it's for the good of their souls!" wore out its shock value sometime in the first Deryni trilogy.)
The Evil Church winds up in a struggle with some sentient coral masterminds who are not, in the event, particularly nicer to hang around with. The human-scale characters should serve as a moral counterbalance, but they mostly spend their time watching the doom and destruction, because morality is irrelevant to galactic-scale political collisions. This is the problem with SF-realist high-tech space opera.
The philosophy is pat, the evolutionary science is pat (albeit generally accurate, credit there), and the space opera doom is wrapped up in a tidy pat ending. A competently constructed example of what it is, but I can't point to anything to recommend it.