Book this place immediately! My friend and I traveled to Lisbon for the first time and stayed here. The apartment is perfect - clean, charming, great light, very comfortable, very quiet. I wanted to move in! Ana Luisa went above and beyond as a host. She met us at the metro station so we could avoid lugging our bags up a hill and even drove us to the airport (although you can easily get there on the metro from this apartment!). She checked in every day, left us some food in the fridge, gave us great recommendations for dinner and lunch places around the city, and on top of that was just really friendly and wonderful! We had no problems with the apartment at all - great water pressure, wifi worked, etc. I am already trying to figure out how to get back to Lisbon so I can stay here again!
Some practicals about the apartment: We were two people so we each had our own bedroom, but you could easily fit more people or a family here. Both beds were large enough for two and I suspect the couch in the living room is also a bed, but we didn't need it, so we didn't try. The apartment is centrally located, right by a beautiful park and down the street from El Cortes Ingles (a huge department/grocery store that will have every thing you forgot to bring). You are a 7 minute walk from the Sao Sebastian station which lets you connect quickly to all four metro lines. If you enjoy walking, you can also walk from the apartment to many areas of the city. (Full disclosure: I live in NYC so I might have a different sense of what is walkable than you do!).
Great apartment. Great location. Great hostess!