Daniel was very friendly and professional and quickly answered all my questions before and during my stay. He also kindly offered to meet me at the nearby Santa Apolonia railway station as I was coming to Lisbon by rail from Porto; the apartment is only about 6-8 minutes walk from the station which also has a Metro stop. The apartment is very well-equipped and the main living area has a big veranda-type window which leaves in plenty of warm natural light.
The location as I say is close to a main railway station (with taxis, left-luggage lockers, ATMs, cafe's etc.) and metro station, so it's ideal for travelling within Lisbon or farther afield. On foot you can explore all the back lanes of the Alfama which is right beside the apartment and a 15-20 min walk, takes you to the beautiful riverside square (Praca do Comercio) while and extra 10 minutes on foot brings you right into the centre of the city.
The only word of caution I would have for older travelers is that the apartment does not have a lift and is on the second floor up two short but steep flights of stairs.