The apartment is located well - close to the city center as well as to the metro (Martim Moniz). Bear in mind that the rooms have really bad quality beds, so if you plan to stay longer, I'd advise you to choose a different place. Our first bed fell apart and did not have a proper bed base, just two wooden sticks that broke. We were given another room in the apartment because of it, but the bed there was really uncomfortable as well. It squeaked a lot, the mattress was really old and hard. Also, the rooms don't have a lot of space for longer stays. Furthermore, we paid for a room with a bed and a terrace, got a smaller room with no terrace because of the broken bed, but no monetary compensation whatsoever.
The rooms got quite cold at night. There is a small portable heater, but it makes a lot of noise and it turns on and off to cool itself down. Not something you can sleep with noise-wise.
The communication with Sergio is easy and fast, but the apartment itself is handled by a different lady who lives in the building opposite to it, she does not speak English.
The room with the terrace has its windows facing the calm street where the building entrance door is, so you don't get disturbed at all during the night. However, the room opposite to it is facing the M.M. square, so you can hear some sounds coming from the street. Proper blindfolds in windows are only in the terrace room.
The rest of the apartment is well equipped, the kitchen is nice and clean, good morning sunshine for a nice breakfast.
Last but not least, the apartment is located on the top floor of the building, so should this be an issue for you, pick wisely.