My family has been getting jap import euro's for years. Never had any real problems with them, and thats for a spectrum of manufacturers over approx 15 years. VW golf, Late 80's 320 Beamer, Audi 80, 93 Beamer 320 (jap option motorsport trim - purple in and out, PIMPIN!) and a 91 260E merc. Merc had a slight gearing prob early on, and needed a fanbelt, but its run for 8 years very solidly.
Service wise, its worth shopping round. There's very little difference in running costs to other cars. The old mans merc was cheaper to service than my civic.
You'll get some features in a jap import that you wouldn't afford in a nz new - the motorsport interior/mags/kits etc. Some standard jap options aren't even featured in the nz news - the 93 beamer had a 5 speed nissan auto box (fun.) for instance.
I'd have little hesitation in taking one. Especially if you have the contacts to import them yourself.