The problem with reading so many books over Yom Tov is you start to realize that all your good reviews sound the same.
Clever world-building; good well-rounded characters, compelling story...
This is because good books, like happy families, are all alike when you're trying to describe them in a paragraph. Johnson's post-apocalyptic world is excellently done, precisely because she seems to understand that certain elements of the world will not change. People can still be good or bad, politics will still be about the hard choices and the trade-off between liberty and control will always be constantly reworked. Johnson explores one particular manifestation of that tension and does so elegantly, with a refreshing focus on the relationship between age and power in a world where life can be extended as well as a quiet but forceful refusal to pretend that sexual mores will not change.
The book itself was a really interesting read, but it was the world with its mix of cultures, its complex development and its artful use of techne (in all the meanings of the term) that really hooked me.