I had the pleasure of staying in Kirsti's apartment for 2 months while I was working and exploring Oslo and Norway during that time.
Her apartment was perfect, very comfortable, has everything you need, and then some. It's in the beautiful St. Hanshaugen neighborhood, which is close to parks, shops and a short ways from city center.
Kirsti was the nicest and most helpful host. She always responded quickly and was accommodating in any way.
I would absolutely recommend her apartment to anyone, whether you're staying for a couple days to a couple of months. I would definitely stay there again!