We stayed for 4 days as a party of 4 (2 couples so cant speak to the comfort of the sofa bed or not) mainly in our mid 30s.
We were flying in at a pretty unsociable hour so a self check in that actually meant self check in (I've had some listings claim to be self check in but meant a building reception or collect a key from the owners relatives shop round the corner within business hours etc) was our number one priority. This absolutely nailed that- lock box by the front door with the code supplied several days in advance with a picture of the box, instructions on how the lock works, directions to the apartment in the building and what key does what door!
It also scored highly for everything else you would want when arriving at such an hour- warm rooms, decent shower, simple wifi and comfy beds.
The location is great, 20/25 minutes from the airport by metro, under 15 minutes walk to the heart of the city, numerous attractions (the little mermaid, citadel, winter palace) within just a few minutes walk- in most cities being that close to the centre I'd worry about noise in a ground-floor apartment, but here there were no problems either being kept up or woken up by any noise.
Within the apartment the communal spaces are bigger than the impression I got from the listing, as other reviews said the kitchen isnt somewhere you'd cook proper meals, but between a cosy lounge area and a good sized table area we ended up spending much more time hanging out, playing card games etc than I'd expected us to do. In the bedrooms the beds are slightly on the large side relative to the room sizes so theres not a huge walking space around- not a problem for us but something that might make me think twice if bringing elderly relatives or those with mobility issues.
Communication in advance was top-notch, they operate a digital guestbook with all the information about the apartment, this scores points with us both for saving paper and it being nice to know everything (right down to a video of how the work the coffee machine and the passwords for WiFi and Netflix) before we even packed.
100% if I were to come through Copenhagen with a similar sized party in future I'd book here again before even searching for other listings.