We had a very nice stay at Elen Sonja's house. Although the host was not there on arrival, we immediately felt at home (we were welcomed by fresh flowers). The communication was always very swift and clear.
The house itself is cosy and well equipped, we found everything we needed. There is a bus stop nearby, it takes you to the nearby city center every few minutes. Oslo is beautiful and there are lots of things to do and see. Our kids and we especially liked the musea on the Bygdoy peninsula (FRAM, Kon-tiki and Norsk Folk museum).
If we ever visit Oslo again, we would definitely try to stay at Elen Sonja's place one more time.