The room was very nice, full of light and very clean. The bathroom was very small but clean and this is mostly all that matters to us so it was ok.
The neighbourhood of Christianhavn is nice and very quiet. The apartment is walking distance from the centre of Copenhague (about 25 minutes) and from the subway (10 minutes).
The only negative point is maybe the fact that we didn't really felt like home at Jesper's apartment. When we arrive, we got barely welcomed by his son (I think) who didn't introduce him to us, and didn't even show us the bathroom (he showed us the room, gave us a piece of paper with the check out and wifi instructions and then disappeared...). We didn't see our hosts during the weekend. We are not intrusive people, and we really love our privacy. But when you are in someone else's apartment, it seems a little bit weird to not talk at all to your hosts... I don't know, maybe it is just us but sometimes, we felt like intruders in this familial apartment. Except from that, all our contacts by message and by phone were really nice, quick and helpful.
In conclusion, if you want just a room to sleep and a bathroom to take a shower, this apartment is really nice and well located.
It is still expensive compared to ohter countries' standards but Copenhague is very expensive. So the price was worth the room :)