Great place; this area of the city is busy and full of life, but at the same time the rooms are totally quiet and separated from the street.
Even though formally you stay at Rune and Kristin's - practically it is a separate small "apartment" (without a kitchen, but with 2 rooms, a large bathroom and a kettle/tea/coffee available). There are 2 double beds, but not very large, so rather for couples or a parent+child. The price is calculated per person but you get a whole "apartment" for yourself, even if you are just two (like myself and my daughter). You are maximum 20 minutes walk from all city highlights (except for the Vigeland Park or the Bygdoy museums, for which you would probably would want to take public transport). In general - I can only recommend you to stop at Rune and Kristin's if you want to spend a couple of days in Oslo!