the best thing about them is how if you momentarily forget where you're going, (!), you can keep spinning till you find the right womb-door.
(disclaimer: i used to love getting on the circle line in london and going peoplewatching round and round for free!)
the worst...italians haven't got the hang of them yet, and sometimes stop and give right of way to incoming traffic....
still way better than stoplights, (boring and fume-y), or the california system of first come first served, (polite, but over ritualistic)..
i bet roundabouts save energy... they sure feel like they do.
as metaphors, they rock. ~"When an inner situation is not made conscious, it appears outside as fate." Karl Jung~