This was my first time using Airbnb, and I couldn't have been happier with Leo's place. It's a nice spacious and clean apartment on a quiet street and in a quiet building.
Importantly, the location is great. It's near many key sites and transportation stops

-Miradouro de Sao Pedro (4-5 min walk)
-Church of Sao Roque (2-3 min walk)
-Carmo Covent (3-4 min walk, behind the convent is the Bella Lisa, which gives a splendid panorama of Lisbon and the castle. Bella Lisa is where the Santa Justa Elavator goes up to).
-Praca Dom Pedro IV and da Figueiro (where you would also catch the tramcars to Praca Commercio and to Belem, 8-10 min walk)
-Praca Luis de Camoes (3-4 min walk, nearby is Manteigaria -- a goto for pastel de nata)
-the train station Rossio (6-7 min walk) to go to Sintra
-Rua Garrett, a key shopping street
And if you're up for staying up all night, the apt is only a few streets away from the crowded and lively bar area of Bairro Alto, but the apt is far enough away and is shielded from the noise.