Let me start by saying the place is spacious and beautiful (not like in the pictures - the colors are different, for the better!). Located very close to the bars of Bairro Alto but in a quiet street, and a walking distance from the city center. Mind that there isn't a lot of public transportation nearby since the surrounding streets are pretty small, so most times you're just better of walking cause that's gonna be the same time as taking the bus or the train ( + bolts are really cheap in Lisbon). And Lisbon has a lot of ups and downs, let's just say it's cardio :)
The double-glazed windows block the noise from outside, but the building is old and if you have sharp ears you can hear a lot from within, yes, including the neighbour's snores :) Also, at some of the time I spent there they were doing some renovation works next door so there would be a little noise in the mornings, so if I wanted to sleep in I needed to use earplugs. Also, while Refael was a super sweet host, and the apartment has a microwave, an oven and a stove, it did not came fully equipped - to the point of there not being any body soap in the shower when I came, no trash bags, no sugar... And in Lisbon there's nothing open at night, so prepare.
Overall had a positive experience, the place looks good and is comfortable, and the area is central and safe. :)