Great location!
Forget the stairs, the building has real character. Turn right and past the church, follow the tram line uphill into Bairro Alto, some great view points and the castle. Follow the tram line down the hill into Baixa and Chiado, and beyond to Rossio station if you want to get to Sintra. Turn left 100 meters and you are into Alfama, cobblestone winding streets and lively and cheap restaurants in the evening, great fun! Go straight down the stairs across the road and you are on the main road that runs along the water front, eventually reaching Mercado da Ribeira, where the TimeOut food market is, and Cais de Sodre station. All of this within 20 - 30 minute walks!
The flat is beautiful, we used the kitchen daily for breakfast, and enjoyed the view across the city, watched the big ships dock in and out of the port.