I stayed at Sunniva and Sebastián's place for two days and I was absolutely satisfied with my stay.
Even though I arrived late at night because of a delayed flight, they still both welcomed me, showed me the flat and we had a nice chat. They are very welcoming and sociable while at the same time let you have all the privacy you need. In general, no oddities whatsoever, felt as if at home.
The flat is tidy and cozy, everything is very clean and looks exactly as in the pictures. It is also very well located - there's a metro stop about 5 minutes on foot away, and from there you can quickly get to most places in Copenhagen, including the airport.
Summing up, I highly recommend this place.