What follows might be most useful for visitors from Ireland and the UK particularly.

Driving in NZ is very comfortable since it is, for us, on the correct side of the road.The rules of the road are virtually identical; to help in this the NZ Transport Agency website has good information about the rules of the road and a test quiz which you can do to see if you are good to go. On the South Island once you get off SH1 the roads are quiet, even in peak holiday time but for comfort and ease I would recommend a maximum of 350km per day. Petrol, at the time of writing is about Euro0.20 per litre cheaper than Ireland. One thing to bear in mind is that there is a culture, maybe it is even a rule, of actually pulling over, and if necessary, stopping to let traffic which may have built up behind you, to pass. You will see the larger campervans and trucks doing this, and if you are travelling relatively slowly yourself in a car, it seems to be expected and is definitely appreciated.

 Motels with prices ranging from NZ$120 to NZ$200 per night will be clean and safe with self catering facilities and friendly, helpful staff. It is not uncommon to be offered milk when you arrive, and for addictive tea drinkers, this was always welcome

Overall, for eating out, groceries, activities, tours etc NZ is I would say 5% - 10% more expensive than Ireland, With the exception of petrol there is nothing that was cheaper than Ireland. 

The country is great for all sorts of outdoor activities, with magnificent scenery, walks, water sports, biking etc etc, but it seems to be a cultural desert. The cities and towns are characterless with no notable archictecture; in Wellington, the capital, there was nothing of interest to do in the evenings and the city was asleep by 9:30pm. This experience may have been due to a lack of local knowledge, but not completely.

People by and large are friendly if somewhat guarded. I was struck by how important the link with the UK still is. The history of the country is very interesting and I was especially struck by the fact that NZ was first occupied by people only 1,000 years ago. I recommend a visit to Te Papa museum in Wellington. The history and culture of the European settlers is very short, 170 years or so, and I have the impression that they are still in search of their own identity.