I had a great experience in Dariusz`s place. The flat is beautiful and so cozy inside!!! Also very clean, organized and silent. Dariusz was always responsive, respectful, very kind and super nice. I arrived in the afternoon and he promptly helped me in and showed me around the flat. The place is just a few minutes from the train and bus stations, just around the corner of a few supermarkets and restaurants (although I only went to one supermarket). Very easy and close to find your way to the main central attractions.
I would definitely stay again in Dariusz`s place and certainly recommend it. And if you are also a solo woman traveler, this is a great place for you to stay (which was one of my concerns before finding a place in Oslo). I also had to leave at 3:45 am and had no problems around there, felt really safe :)