Keith Roberts' genius is mostly remembered for the much earlier Pavane, but I got to Kiteworld first and I prefer it. Despite the direct borrowings from Wyndham's Chrysalids it's a classic of British SF, describing the last days of a grim world, painfully built up and barely held together against horror.
The storytelling is like Pavane: a group of vignettes and episodes with overlapping characters. The Kiteworld is a desperate, isolated society at the limit of its resources, teetering on the edge of civil war. The unbending cruelty of the Church Variant anchors the race to the litany of the true human form, while the duty and sacrifice of the Kites defends the Realm against remembered demons of the air. As the oil wells run dry, outsiders and fundamentalists are waiting.
The scenario matters, but a work like this depends on detail and texture. The Cody kites run all the way through, and Roberts uses their intimate chandlery of cables, cones and dope, their winches and ships, their ledger-led bureaucracy and mad or broken military servants to paint the entire world. The damaged, very human, very ordinary inhabitants of that world demand our sympathy despite the flaws that Roberts relishes into them.
Roberts is set aside from the more acknowledged greats of his generation by superior writing. It's the reason to keep coming back when others can be left as safely read and done. Sometimes it seems as though it would be easy by mistake to incorporate his vivid scenes into one's own memories: the smell and sensation of a risky launch at a remote station, or the stone streets of a decaying port town.
This is a book of the Eighties. Its concerns are mostly Eighties concerns -- nuclear apocalypse and radiation, UFOs and resource depletion. But it's classic SF and as good now as it ever was.