I've read many posts which say a GPS isn't necessary in South Island, however I am 'directionally challenged' (to put it mildly!), and would feel more comfortable if I had one, even if just as a backup when we are looking for places within the bigger towns, etc.
I own a TomTom device and have taken it abroad previously. Hertz also offers their own system with the rental car (Neverlost GPS). There isn't much difference in price. Does anyone have experience using both systems in New Zealand, and which would you recommend? I read a couple of bad reviews about the TomTom NZ maps, but couldn't find anything recent...