I started ski-ing at Whakapapa a couple of years ago. I am a NZer from the South Island (Queenstown) and have skied in Australia, Austria, Germany, Switzerland, Canada and Scotland.
I agree, the night-life is pretty well non-existent at Whakapapa, but not for the entire NZ ski scene, as one reviewer suggested. I can only assume he or she has an unsociable personality, because Queenstown nightlife is a wonderful beast and has been for many decades. Anyway, back to the mountain. Some of the lifts are oldish, but others are new and more are planned - you can check this out on their website. They certainly carry a lot of skiers which is what matters, and the mountain has an excellent safety record because the staff are very professional.
NZ snow is water-heavy and so powder on our fields is a rare thing, though we call light snow powder and ski it happily. It isn't 'patchy' unless it's a bad season, which affects many ski areas at lower altitudes, which is where ours are. Whakapapa is prone to icy snow however, so you should learn how to ski on it. Everyone has to at some stage. In the late spring you sometimes ski on corrugated iron in the morning and porridge in the afternoon.
The views are spectacular and there are some great trails, some well worth hiking off-piste for, though be sure what you are doing, and if it gets misty, don't make guesses about where to go - just wait for it to clear. There are some dangerous drops.
Last time I went I skied all over the mountain, connecting with my friends easily by texting them - aren't mobile phones just great in the mountains? This year I bought a season's pass because it is cheap (just under NZD500)and because the mountain offers a good variety of terrain.