Hey I was born and bred there, and visit family there often so here's what I think.
Chch is the biggest centre in the SI and has a population of 350 000. This is a good size because it is big enough to have facilities eg theatre, symphony orchestra, aquatic centre but small enough to make travelling around the city quick and easy. It was a planned city for immigration so the roading system is systematic. While it is true that housing prices are cheaper than Auckland (everywhere is cheaper than AK), the prices are not as cheap as they once were.
Christchurch has a number of very good schools, one thing that I miss here in Tauranga.
There is a definite "old boys" system when it comes to schooling, a perception about what sort of person you are depending on your school and the suburb you live in. Its the only place I know where in the introductory part of a conversation people are likely to ask adults what school they went to.
Because the city is a long way from other population centres (about 6 hours from Nelson and no one ever seems to go to Dunedin), it can be a little insular and smug. However, it has a neat cultural heart. Walking through the Arts Centre on Saturday mornings, viewing the market stalls is fun. THis is near the Museum, Botanical Gardens, new Art Gallery (very cool building).
The Beach is terrible, cold and windy, but ski-fields, bush walks etc are very accessible, as is sailing, and all manner of sports.
The city is very white ethnically, very few Maori and Pacific Islanders cf Auckland, but there has been an influx of Asian immigration which has unsettled some of the inhabitants. In the city centre now there are a lot of specialty Asian supermarkets and shops.
Winters can be cold and grey (and a bit depressing). Summers hot and dominated by a the Norwester (a hot dry foehn wind) which can upset some people.
There is also quite a decent university - Canterbury (i went there).
I think that's about it but if you have any specific questions please feel free to ask. It is quite different from the North Shore so if your husband is happy there he may be not so keen on CHCH