We stayed for a few days. The best thing about the apartment is definitely the location - it's great for a short stay in Copenhagen. Probably better for solo travelers rather than couples though.
Something that we found inconvenient for us is the shower room. We expected that the basement shower meant that it was fully private and just a flight of stairs away. In actuality, it's a semipublic area that is several flights down and across a small yard. It's more similar to a hostel in this. We thought that the shower wasn't very clean and small.
One thing we liked was the kitchen, since we like to cook ourselves. There's also vintage furniture that is very comfortable and some cool art on the walls.