Christer is a very kind and helpful man, he resolved all our doubts. His home it's awsome, confortable, cosy, it's in a beautiful neighborhood, with a good location, you can go and back from the downtown very easy and fast. The transportation is good, and a great view of the city from the 8th floor!
If you go to Oslo, Christer's home is the best option for you, I would definitely go back and stay there again.