I have lived in both places - Dunedin i really found that the older people treated the younger people with much less respect than in Christchurch...I'm guessing it has something to do with students etc but it was bloody annoying! esp in work! as because you appeared young you were quickly treated as a junior...even if you happened to be a senior! pay rates are also stink as - cost of housing is similar if not more than chch if you want a place that has a garage and isnt going to freeze... (I only lasted approx 11 months in Dunedin before moving back to Christchurch)
Christchurch - friendly people generally, lot more opportunity - better pay rates, better housing, and the climate dominates dunedin.
I live in somerfield, always lived around this area somerfield/barrington/lower cashmere - have had 2 cars stolen in the area, 1 even in a garage...any where you go your car isn't safe, get insurance and the best alarm you can afford.