Though it was only for one night, we enjoyed our stay at John and Hilde's. They were very welcoming and Hilde helped us get oriented in Oslo, pointing out all of the important sights for our short time there (which were all within walking distance).
The room was very clean and the bed was really comfortable. It was also nice to be able to drop off our bags when we arrived in the morning even though check-in wasn't until later in the day.
We would gladly recommend staying with John and Hilde, and would stay again ourselves if we ever return to Oslo!