Could you take a sabbatical first to really get to know it? I know 3 couples that moved there plus us, and no one lasted longer than 3 years.
I love NZ for lots of reasons, particularly outdoor activities, but it's not the paradise people think. You need to choose location very carefully because weather and culture vary massively between regions. It could be amazing but go in with your eyes wide open.
Food is so expensive and choices really limited. Its not just a case of eating seasonal you have to get used to boring and out of date too. Crap bread, crap cheese, crap restaurants, much harder if you have any kind of dietry requirement.
Culture in some areas is more comparable to rural america, gun culture and conspirisy theories. Drugs, MH, homelessness as people have mentioned too.
Overt racism, particularly towards Chinese and Asian people.
Everything much more isolated so there's no nipping to another city for a gig unless you take a flight. Every other country is far away.
Animal welfare is quite shocking in some sectors and poorly policed. And despite the clean green image its ecologically devastated.
Collective delusion over how amazing the country is. That's one of the weirdest things!