I remember when they installed one out in Littleton (suburban Denver) - it flows traffic spectacularly but it took years, maybe even a decade for people to get used to it.
I once came upon it and found a full size four door sedan in the (raised) island in the middle with four befuddled teenagers standing around shaking their heads. They had plowed into the traffic circle straight ahead, jumped the raised embankment and landed right in the center island.