I'll steal the description from Wright: "it was like a Jack Vance novel written in AE Van Vogt pacing." I like Vance's avalanches of creativity.
The thesis is that humans colonized a planet that had lots of life (no animals above insects mentioned), apparently out of desperation. The problem Kingsbury noticed is that the native life won’t have the same DNA and proteins, and no matter what it looks like it won't be good to eat. And getting our native plants to grow is way trickier than it seems, since down in the dirt it depends on lots of microorganisms that may not get along well with the native population. Result: very insecure lives, and the most important class is the bio-engineer types (called priests). (All quite logical, and I'd not thought of it before.)
The story opens with a cannibal feast at the death of the leader. (Food doesn't get wasted.) Three brothers are survivors of a crèche (3/4 of children there fail tests and are eaten). The story opens with the three brothers and their two wives (one marriage) being told they can't marry the woman they want (a brilliant physicist), but for political reasons have to marry a heretic in another tribe who teaches that people shouldn't be killed like that.
The various tribes are breeding for intelligence and strength and "kalothi", and by the end it is fairly clear that they are smarter than normal humans (except when somebody has to be tricked for the plot's sake).
On the plus side it has, as Wright said, Vance's creativity with good pacing. The reader is introduced to strangeness, and you have to think carefully about what is really happening. What is and isn't possible in the environment is also well thought out. On the minus side, the history they learn partway through induces too-rapid changes(*), and the subsequent quotation mix is a little jarring. And the characters are inhumanly sexually easy; only one shows anything like jealousy and that only intermittently. And I think the food energy budget is a little off, but that's a quibble.
It is well written, well thought out, overall well-done; and yet... I didn’t like it very much. The themes and background were off-putting enough to make it unpleasant.
(*)I work with people doing cutting edge stuff, and can assure you that Skylark-type "prototype to production model in 6 months" is wishful thinking. You discover things the manufacturer didn't know about your components when trying to make something new.