When we arrived, the pellet heater was going, and the place was warm. This is important because Twizel can get quite cold in the winter. The rooms have wall heaters, but the only heat pump is in the hallway. The master bedroom got a little cold at night with the door shut, but it wasn't uncomfortably cold or anything. If you keep the door open, the heat pump will warm the room sufficiently.
Let me provide one cautionary tip: on cold nights, the wooden steps are extremely icy and slippery, as are the steps leading to the house.
The living room couches are very comfortable, and there is a fairly large, modern tv with a full speaker system. I can't overstate how much heat the pellet heater can throw out. You can roast yourself quite nicely with it.
The kitchen has pretty good amenities, and features a propane stove. If you're used to gas, propane seems to get hotter, so watch how done your food gets. There's a functioning dishwasher, and excellent water pressure and hot water. There's also a milkshake mixer in the kitchen that the kids were elated to discover.
Two of the rooms feature bunk beds; one of the rooms has double bunk beds. This house can accommodate a fair number of guests comfortably. There's a warning about blowing through all of the hot water, but there were 7 of us and we didn't have any problems with hot water.
If you're staying in Twizel, I'd highly recommend this house. You'll be warm and comfortable.