Pedestrian either have pedestrian crossings or pedestrian islands provided along each ingress/egress road. With ped crossings obviously cars give way to peds immediately, and there is no distraction because at that point you are still on a normal road. With the islands, the pedestrian moving into the middle first when it's safe, then onto the next side. Pedestrians don't walk onto the roundabout itself.
Roundabouts are used in low and medium volume traffic situations, where it is quite easy to find a safe gap to walk across a road. It does mean a bit more walking for someone trying to walk 'straight' through the roundabout, as you'll have to deviate slightly down a side road then walk back up again. But as mentioned, since there isn't normally much traffic, you don't normally need to walk far. It's normally quicker than waiting for a traffic light.