I spent 2 months and a half in Oslo because of my studies and I can say that Martin was a perfect host ! He is a nice person, very easy going. He also gave me some tips to enjoy Oslo during my stay.
Concerning the apartment, it is very clean and lovely. The bedroom is cute and I had enough place to store all my belongings.
It is very well located, 3 min walk from the bus stop which goes to the city center.
I can only recommend!