While it's a bit cliche to say it's the perfect location, the apartment really is in a great location. We walked everywhere, except the maritime museum - mostly because it was our first day and we had travel fatigue. It's really very central.
The apartment is in a very quiet neighborhood.
Even so, you confront an almost infinite number of restaurants and clubs within a five to ten minute walk radius. Francisco recommended the KOB restaurant. Top notch if you are a steak fan. It was the finest meal of our trip, though it's not cheap. We found many cheap and excellent choices as well, including Zero Zero Pizza, Esplanada Cafe in the park on Principe Real, Mamie Rosa and Cafe Brazil, Lda (R. São Pedro de Alcântara 51) where mostly locals gather. Find both in the absolute sea of good places in the ten minute walk radius. Also recommend the Sangria and sandwiches at Bamboo outdoor bar under the trees on Liberty (turn right off Gloria onto Liberty and walk maybe 200 meters - last one before the square). (We do not recommend A Gina.) None of those places is a ten minute walk. If anything, the problem could be too many options - if choice is a problem for you.
Apartment isn't large but is comfortable, private and secure. It can get warm in the loft on very hot nights.
Francisco is a genuinely helpful host, and we appreciated the top notch vino that comes with the apartment, as well as his willingness to field questions along the way.
All said, it is a very nice place and we would stay there again.