I stayed at Espen's place with my family (my wife and 4-month-old daughter) for two nights while visiting Oslo to present at the conference.
The apartment is nicely furnished and we had a good stay. What I overlooked during booking is that Espen had only two single beds and we needed to have one double for my wife and a kid. But everything turned out well - we moved folding bed next to the sofa and they happen to have exactly the same heights to it gave us a double bed we needed. So you can have one double and one single if you need them.
Another nice thing is that you have a grocery store just next door plus many restaurants in the area.