I'm living in Germany, where roundabouts are very popular with planners recently. I would say they definitely have their place, but they are also overused. The (smallish) city where I live has a bypass road where for some reason it was decided to use roundabouts (I suspect the same reason why it has so many tight curves - not wanting to purchase too much land). With the result that using the bypass is not much faster than driving through the town, so barely anyone uses it.