Margarida is really nice and makes things work. The house is near the top of the hill and has a little view toward the river, and a nice breeze usually. I was there in mid-August. Mornings and evenings are lovely. The bus line is nearby and runs about 630 AM-1030 PM. Walk to the river is about 20 minutes downhill, and 30 minutes uphill. Very good transit train/bus/trolley main lines. Reasonable taxis. Lisbon is a very safe friendly city with lots of things to do, interesting reasonably priced food and a wonderful diversity of people and public spaces.
I went to Lisbon for Nos Alive, Margarida's house is close to the venue, it is a perfect place for someone who doesn't like festival camping. Her house is in a safe quiet and beautiful neighborhood, she runs this place delicate, I can feel sweet European family the moment I entered the house. With bus 729 you can get to the center quickly, Lisbon is a small city anyway and the buses are easy to understand. I would definitely recommend her house.