I do not have much experience with hostels, but this place exceeded my expectations. We were at Dwellington for 2 nights with 3 kids. Most important points to make a choice were: Good Price, New World grocery store across the road, just a few minutes walk from Wellington railroad station (to which Northern Explorer arrives).
There's a great shared full kitchen with everything needed for cooking: stovetops, ovens, all possible utensils pans and pots, a big fridge and shelfs both with labelled containers to keep guests groceries.
There's a cinema, and a lounge with lots of board games guitars and national geographic magazines collection.
At a moment when we were visiting all guests were nice and friendly and there was some sense of community, many of them were gathering every night and playing some games (we didn't participate however).
Every morning some stuff for breakfast provided: bread, spreads, sometimes fresh eggs, fruits, great filter coffee (I think it was Havana brand), cereals and flakes, basically a good base for breakfast.
Backyard looks good, but unfortunately it was raining and cold.