Here in W. WA, they apparently have to take them in Fours, so they install four of them, often quite close together. Here are some of the problems:
* They build the centers high, so you can't see over them, or if someone is coming.
* Most of the young guys try to take them as fast as they can. Since you can't see over them, if you don't see anyone coming, you pull out just in time for the mental midget to come flying around, almost on two wheels.
* In residential areas, the center divider is raised AND planted with trees close together so no one can jump the median -- like paramedics and fire trucks responding to an emergency -- so these emergency responders have to go all the way down to the next roundabout (sirens blaring), and there always seems to be someone who just can't wait, and charges out in front of them.
* There often aren't any warning signs on what the coming cross street is named, so some drivers don't realize this is the place to turn until they're right there, and then they slam on their brakes to slow down enough to make the turn. There are often broken red tail lights decorating the pavement.
* Some of them have the little surprise of lane reduction right after the roundabout -- you are in the right lane of two lanes, go halfway around, start going straight and then realize that you have to merge left, and the left people aren't going to let you.
* WA drivers think turn signals are either optional or simply decorative; sometimes they use them, sometimes they don't, sometimes they use the left one when they intend to turn right.
* Some people fail to make the turns (probably going too fast, which is very popular), and they skid into someone's front yard.