I moved to New Zealand from Dundee last June so I have a year under my belt and have done a lot in that time - travelling to a lot of places in the north and south island.
I moved with my work - basically switching offices (we have one in Dundee and one in Auckland - Kumeu to be precise) so that side of things have been really easy. I already knew people I was going to be working with and my work remained realtively unchanged. I'm currntly living in a suburb of Auckland called Te Atatu peninsula, so not in the city but it's only a 15 minute drive away. One thing I will say - and it's important if you do consider living here, is that 15 minutes going towards the city at rush hour can easily turn into an hour. I'm lucky, as my commute takes me in the opposite direction to the main flow of traffic so I have a 20 minute commute each way.
Auckland is a terrible city for tourists. Public transport is shocking, it's not a 'pretty' city (infact, the aesthetics of a lot of Kiwi towns leave a lot to be desired. I think in britain we're spoiled by grand old buildings and a general sense of cohesion in architecture and highstreet visual standards), and it's pretty spread out. You can't spend a day walking around the city like you can in more metropolitan places like san fransisco, melbourne, barcelona, edinburgh etc. and that space leads to a certain sense of social distance while living here too. All your friends live not within walking distance, but driving distance. Which kills the idea of nipping out to the pub or catching a drink with colleagues on a friday evening.
BUT, it is a good city to live in. Once you get to know the place, you learn its secrets, the food, the parks, the markets and shopping districts etc. There's a lot going on in Auckland - you just need to dig a little.
So where you might want to live depends really on what kind of person you are. Coming from Dundee which is a small, hyper-social city - I'd have been better placed in Wellington, honestly. But that doesn't mean I don't prefer Auckland to Dundee.
However, the city you choose to live in is not representetive of New Zealand. The whole country is designed around being outside. And that outside is nothing short of magnificent. I can take a 45m ferry from Auckland and be climbing a dormant volcano. I can drive to the west coast and hike in aincient forests or go surfing. The east coast is great for swimming and snorkelling. To the north I can mountain bike and further north is no shortage of beaches (that are basically tropical in nature) and more hiking. I can take a weekend to go skiing in either the north or the south island. The South Island is just other wordly, with incredible mountains, glaciers and multi-day hikes.
Summer is actually summer here, in that it lasts for months! and the winter isn't even that bad! if You get a sunny day in winter - that's a perfectly usable day! I was camping last winter while trying to discover the country a bit and that was pretty much like camping in summer in scotland
Life is more laid back for sure - people value their free time more than time in work (as evident by the number of bank holidays!) and people are friendly (like the scottish).
Go for it.
Edit. I'm also 30ish, if that helps. And wanted to add, I can't tell you how much of a relief it is to live in a country with a competent PM