Oscar's place is awesome as it has a great view over Oslo (normally - it was very foggy when I was there ;)), and both room and bathroom/kitchen are very comfortable and nice, too!
He was very welcoming in the beginning, and very reliable concerning communication! Tip top!
The apartment is 5min walking-distance to the central station which is great for exploring Oslo (all important buses, tubes and trams stop there) as well when you have to leave for the airport early in the morning :-)