I joined KiwiSaver as a recent immigrant when I joined the local workforce. At age 41 I have $50K of superannuation in Australia (which now I will probably only be able to access at age 65, given that pension age is now 70 for people my age, and preservation age will keep step at 5 years ahead of pension age) so my KiwiSaver will be supplementary only to my Australian super + my own stash. Therefore I have chosen a fund with an aggressive strategy (AMP One Path Aggressive) seeing as there's not a whole lot there and it has 25 years to do its thing. A bit of a flutter.
As an Australian with its then 9%, now 9.5%, compulsory employer contributions, coming to NZ with its then 2% now 3% scheme was interesting in that they hadn't gone nearly as far. I am all for it, though. NZ has non-means tested pension - another difference between the countries.