I've spent a week in Paulo's place and I had everything I needed to feel safe for my stay in Lisbon.
The place was clean and cozy and conform with the description, the location is few minutes walking from Apolonia Station and close to Alfama and well connected by public transport and also very close to Feira da Ladra- very interesting flea market that happens twice a week. As others mentioned, I would advise to bring ear plugs-normal street noise of a big city could affect some light sleepers.
Paulo was a great host, very easy to communicate with, he was very kind and waited for me at the train station and gave me good informations about the city and how to get around.
I recommend this place for solo travelers or couples and Paulo as a host when you stay in Lisbon. Thanks, Paulo!