We had a great stay in Sergio's apartment!
The apartment's location is amazing, really you are right in the heart of Alfama, with lots of bakeries, restaurants, and beautiful lookouts close by. The apartment itself gets beautiful light and views. We were worried that it would be too hot at nighttime, but while we were staying (September) it was beautiful at night with a cool breeze, so perfect temperature to sleep. The internet is also very fast and convenient as you can carry it with you and it is 4G. It is worth noting that there are steep stairs to get up to the apartment, in case you have any mobility problems.