This was an amazing experience, even in the height of summer! It was the best place we stayed in during our trip!
It was very clean, comfortable, and had such good attention to detail (included eye masks, ear plugs - though that was unnecessary since it was very quiet, and a nice note on where to get breakfast).
The igloo was warm when we arrived because it was such a sunny day, but opening the vents made it a comfortable temperature in no time. During the night it did get cooler, and the heater was necessary. They also had heated mattress pads, which we didn't need, but I can see being great in the colder months.
The private igloo is definitely the way to go, though with it's own bathroom and shower.
We were very comfortable the whole time there and will be recommending it to everyone!