But a few trip notes are in order.
Forget about it. You won't find much, and what you will find is metered at very high prices with poor performance. Feel free to take out a second mortgage to pay for the international data roaming charges on your cell phone if you prefer. Or just go mostly-to-fully off the grid while you're there.
The country is full of clean, well-kept bathrooms which are available at almost every stop you will ever make. They universally include a toilet brush, which is important when you live a toilet-based lifestyle like me, and wish to be a polite guest. However, every single bathroom in the country is unheated and apparently uninsulated. Most of them are cold enough to hang meat, or serve as an overflow morgue should a pandemic strike the country. I think there must be a law mandating that bathrooms be below a certain temperature, possibly to inhibit bacterial growth. This means that if you spend a lot of time in bathrooms, as I do, your odds of contracting a respiratory infection from lengthy sitting about in the frigid air are quite high, and your odds of fighting it off once the infection sets in are virtually nil.
New Zealanders are almost without exception pleasant, genial and quite happy to see you (and your tourist dollars, I suppose, but I was never once made to feel like a mark). They are however somewhat vague on the concept of customer service or operational efficiency. So while everything happens eventually, and usually with a fair amount of good will and bright demeanor, it doesn't always happen when and how you might wish. This ranges from restaurant ordering to hotel check-ins to purchasing things in shops. Be patient, it will all happen.
Air New Zealand
Just don't. Not if you can possibly avoid them. Air New Zealand is an utter disaster from the traveler's perspective. Their in-flight equipment and service was good-to-excellent, but their on-the-ground customer service would shame a failing hamburger stand in Zimbabwe. Broken Web sites, inconsistent fare quotes, third party contract staffing at airport desks with no ability or authority to help a traveler with a problem, weirdly strict domestic travel rules with no exceptions or workarounds. Basically, they have no capacity to handle exception management. Air travel is made of exception management. But that's not the Air New Zealand way. It's that genially vague customer service ethic gone utterly toxic. (I'll post details about these issues soon.)
Everything else about the country was excellent. The food, the people, the landscape, the cities, the attractions. It was like being assaulted by natural wonder at every turn.
Go, spend lots of time there. You'll never have a bad meal, and never meet a grouchy Kiwi. Just take note of the above to avoid disappointment.