I stayed at Maria's place for two weeks while I was in Lisbon working with colleagues at the university. It was perfect for my needs. The apartment itself is spacious -- 4 bedrooms, 2 bathrooms, living room and kitchen -- and has all the conveniences you need, like strong wifi and plenty of hot water. It has beautiful wood floors, a lot of light and was spotlessly clean. In nice weather, you can sit out on the small balcony. Unfortunately it rained most of the days I was there!
The location is also excellent. There's a grocery store across the street, plenty of places to eat around the corner (including Laboratorio do Gelado sub 196, that makes ice cream on demand with unique flavors!), and great laundromat about 4 blocks away (Lavandaria Self-Service LavaMais). There are several parks nearby for running. From the apartment to and around Campo Grande was just under 3 miles. The metro is literally a few steps from the apartment building and takes you to the heart of downtown in about 15 minutes. Maria was a great host -- I would definitely stay here again.