We had a very nice stay at the apartment. It is close to metro and also only a short walk away from the city center - but beware that it lies on top of a hill, so you have to walk uphill to get there. It's not the most quiet area, but probably better than other areas in Lisbon as well. The apartment is minimalistic, nice and cosy and had what we needed for our stay, and the hosts were very available and helpful, when we needed local advice.