Great apartment and excellent location. There are some stairs up, but that is not a problem if you are in normal shape. The apartment is big, but it has only two bedrooms and one bathroom. So, if you are more than four in your group, the others need to sleep at the mezzanine (which is fine, especially for the youngsters, although not suitable for the very young).
The apartment is great to make food in and have some friends over. But be aware of a very sensitive neighbor underneath. Jakob was easy to communicate with before we came and gave us all the necessary information we needed. Under our stay we found out the we got faster answers with sms, then by using the Airbnb-connection.
The apartment is excellent located in the neighborhood of Christianshavn, and close to bakery, grocery stores and bars/cafees. It is only a nice little walk to the city center. Is was very easy to get there from the airport with the metro. From the metro station is was only about 200 meters to walk.
I would recommend the apartment to other fancy a few days in lovely Copenhagen.