The location is great. There are some nice restaurants and bars in the vicinity (try Este bar after 10pm!), you can have great breakfast at Copenhagen Coffe Lab, and there's a friendly craft beer store nearby.
The apartment was sparkling clean and well-equipped.
One thing should be kept in mind before you book the apartment, however: its sound-proofing is not very good. You can basically hear everything that happens in the apartment above. (Which at the time of our stay meant two kids running around like crazy <3) Also you should walk around very carefully, as there's an apartment below, and we had some complaints about stomping loudly, even though we were walking about in an ordinary manner.
I'd still say that's a trade-off well worth making because of the apartment's overall quality and favourable location.
Some remarks regarding check-in:
1. The door was initially closed, but not locked. The door latch is opened by turning the key counter-clockwards.
2. The address is No. "7", not "7 1". The door is right next to 7A.
3. The apartment is behind the first door to the left when you enter the building, downstairs.
4. I recommend approaching the building either from the Martim Moniz or the Santa Apolónia metro stations. Santa Apolónia is a bit closer by foot (10 mins), but if you have lots of luggage, you might want to take the 28E tram from Martim Moniz instead, as you'll have to climb some fairly steep hills to get to the apartment. (Keep in mind that the 28E can be very crowded during daytime, though.)