I have done the trip many times since AirNZ took over the service. As Fruitcake says it is typical trans-tasman or pacific islands service so very basic. For the extra payment you receive an additional bag (23kgms), priority check in and boarding, meal and drinks and included access to all movies plus access to Koru Club. You are seated in the front 2 or 3 rows and will have a vacant seat beside you if the aircraft is not full. There is no Koru club on the island so you need to consider if the other benefits are worth the cost when you return. Food and drinks and movies can all be purchased on board.