I saw a tractor trailer fail to stop and subsequently jackknife in a roundabout in Louisiana. He's lucky he struck no one. Roundabout or not, he should have slowed down, especially since it was damp pavement at the bottom of a freeway offramp. I can't fairly blame the roundabout, but then again it's the closest I have seen a fellow trucker come to a major accident. Color me skeptical. Either eliminate them or go all-in for these things. Kansas and Wisconsin seem pretty committed to them.
I haven't driven much in the states (did drive a 71 pre-federal spec Stingray!), but I certainly prefer a roundabout to a 4 way Stop. It is what we are used to in the UK. They have even started building new housing estates with roundabouts installed, even before the developers start putting up the houses.