We've had a wonderful stay at Halvards Apartment. After our search through Oslo (check if the navigation sends you to the right location!) we arrived and immediately were very enthusiastic about the view from his place. The combination of city sounds and the mountains in the distance is soothing. Our morning coffee and afternoon drinks on the balcony has been highly enjoyable.
On top of that Halvard is very open and approachable. We received splendid tips about where to go and eat (Hrimnir is one of them!). From his apartment it's just a short walk to the bus station which is two stops from the central hub.
In short: great place to stay. Kind and approachable host. Nice and enjoyable apartment with a great view and good travel options.
Also.. Oslo is an awesome city!