I can completely recommend Laith's apartment as a clean, comfortable place to stay. There was very good water pressure so showering was a joy in the newly fitted bathroom. It has all the amenities and Laith is very responsive to address any concerns to make your stay enjoyable. It takes about 15mins to get into Oslo centre with local bus departing arriving every 3-7 minutes. Download the Ruter# app to buy your tickets (easy!). The bus stop is a 3 minute walk from the apartment. Just across the road is a large food supermarket and pharmacy which opens from 0700 to 2300. Getting to the apartment from the airport, train station via bus is straightforward and inexpensive.
My daughter and I would certainly stay there again and comes highly recommended!