We stayed in a powered site at Milford Sound Lodge over New Year's Eve/Day. Despite the torrential rain and wind putting a dampener on our touristing plans, the Lodge was a great place to seek refuge, hang out in the warm lounge with a hot chocolate and generally make the most of relaxing time in the wilderness.
The sites are well located with gorgeous views - we had one facing the river and were treated to the amazing site of impromptu waterfalls down the mountains after the heavy rain. Facilities at the Lodge were great for what we needed - clean bathrooms/showers (and plenty of them), ample kitchen/dining room and cozy lounge. The shop stocked basics and the wifi was an expensive (understandably) but unexpected benefit - great to be able to keep semi-up-to-date with the world outside thanks to satellite internet.
Most importantly, the staff were friendly and knowledgeable, keeping us up to date about the road closure and weather over New Year's. Will definitely be back - gorgeous place to spend a few nights.