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.

I know there's a few, but I don't tend to pay much attention to them since they're kind of part of the background.

The one I can definitely place is the Manners/Willis/Boulcott intersection, which as far as I know has been there for decades, but I know there's more, mostly in the CBD end of town. It feels like they may be becoming gradually less common though?

Christchurch has had them for over 20 years.