It's a great place. The apartment has all the needed equipment, it's clean and it's close to the São Sebastião metro station and the El Corte Ingles mall. You can even walk to most places in central Lisbon from there, if you like to see things by foot. There are many windows inside the apartment so it's easy to get fresh air inside, which I really like. There could be some construction noise outside in the morning, but that is to be expected in a big city like Lisbon.
I didn't meet Ricardo personally, but he was always very fast to answer questions on the phone, and very friendly.
So overall I think the apartment was great and I can definitely recommend it to anyone wanting to stay in Lisbon.