Yep, ITM Cup is really entertaining for sure, best part is every part of NZ is represented so the smaller areas really get behind their teams. Also, during the ITM Cup teams compete for the Ranfurly Shield, which is basically like a boxing title belt. You have to defeat the current Shield holder on their home ground in order to take it from them, and when you win it you spend the next week touring around your region to all the small towns with it, Stanley Cup style. I went to a Ranfurly Shield defence a couple years ago in New Plymouth and the atmosphere was great. They had a parade down the main street before the game to show off the Shield. It has no effect on the overall standings or playoffs, but is a little bit of extra prestige in the competition.
More info here:
https://en.wikipedia.org/wiki/Ranfurly_Shield