Kevin has a number of apartments available in the same area of Oslo city centre. These are a walk of a minute or two from the fjord, from several restaurants and coffee shops, and from a 'convenience store' and a supermarket. The central station and opera house are a very pleasant 15 minute walk away. So location-wise these apartments are great!
They are also spacious, clean and well-equippped. I don't know if they're all the same but ours had two balconies, good wifi, a Bang and Olufsen TV, a washing machine and a tumble dryer, and two shower-equipped bathrooms.
Kevin was also a great host, meeting us on check-in (he lives nearby) and facilitating a late check-out.
All in all, highly recommended and will definitely aim to stay here when next in Oslo.