If you are visiting Oslo, this is one of the best places to book. Walkable location to the top restaurants in Oslo. Walkable location to the best bars/pubs in central Oslo. Walkable location to the museums and Oslo fortress, and much more.
One street above the apartment you have the best bakery Backstube in Oslo. So far, for me, this bakery had the best coffee in all of Oslo :) (and a pretty cheap one).
During our 4-day stay, we didn't feel any need for public transportation and we visited everything on walking.
The apartment was clean warm and spotless. It has everything that you need, including fast internet and a quiet environment for freelancers like myself.
There is not much to add, just that we are planning to visit pretty soon again and we will definitely pick this apparent as our first choice.