In New Zealand, the most extensive bus company is called Intercity. There is also Naked Bus, but I never took them as they could never undercut Intercity on price for me (and I never heard the best things about them anyway). There are also local systems, especially on the South Island (Atomic comes to mind as a big one) but since I never took anything else, I can’t give an opinion either way. Intercity buses are fabulous for point to point transport. The more in advance you book, the cheaper the ticket (NZ$10 one-way from AKL to ROT!). The buses are super clean and the drivers are always friendly. The buses stop every 2-3 hours for a bathroom and tea break as well and that time in factored into the trip. As well with everything in NZ, everyone is trusted and I have never had to show a ticket when I board, I just give the driver my name and on I go! Don’t even need to show ID and not needing an actual ticket is helpful for those too cheap to pay to print (always me).
Since it’s mainly locals on the buses, the rides are usually really quiet but sometimes the driver throws in commentary, which from a tourist point of view was always welcomed by me. One time, on a trip from AKL to WLG, Mt. Ruapehu had erupted earlier that week, so the driver pulled over on the side of the main highway/road (common occurrence) and we all got out and took pictures!! But on the way back, we just had a very quiet drive, which was fine too. The first time I took the bus was my first Easter weekend because I was nervous to drive on the other side of the road and everyone told me holiday traffic would be out in full force. It was a lovely ride, but it was then I realized that my definition of traffic was waaay different then NZ. I went to Rotorua for the weekend and ended up hiring a car for about 3 days once I arrived because the town is so spread out. I don’t regret taking the bus, but going forward I didn’t use it for 3-4 hour car rides that were return trips.
Moral: I wouldn’t recommend them as your sole use of transport as a tourist, but they are super useful for those point to point trips.