Auckland has had a few for at least 10 years. They are used for some of the very busy intersections on Queen Street (a busy shopping street that also carries a lot of cars and buses), and seem to work well. Regarding Wellington, I can think of only one, which I think was put in a few years ago at a 5-way intersection that had a lot of foot traffic and was quite accident-prone; I think it's been successful in simplifying how pedestrians use the intersection and reducing accidents, and doesn't seem to have worsened traffic flow.