What isn't wrong with them? They require too much real estate, relative to a four way stop or a traffic light. The Fort Collins City Council argued for years over a proposal for a multi-million dollar roundabout, only to be defeated by a coalition of defensive landowners and fiscally conservative taxpayers. Now they have a functional four lane stop light. The residents of Vail weren't so lucky. By the time one has turned 270º to negotiate a simple left turn, one has forgotten the point of the exercise, misses the desired exit and must circle again. One never knows who has the right of way--the person trying to enter or the by now desperately claustrophobic person trying to escape. Homeless people camp out in the greenery in the center, making the neighborhood unlivable with the stench of their urine.
Earle Society for the Prevention of Excessive Wroundabouts.