Alfama is unbelievable, and the flat is in a perfect location: a short walk from the underground (Santa Apolonia) but at the same time right in the middle of the neighbourhood. The flat is very nice but keep in mind that it's at the fourth floor with no lift. We visited in "winter" (if you can call that winter!) but in summer it must be very hot because it's south facing. There is A/C though and it works well.
The host emailed us very detailed local tips for restaurants, shops, and places to see, which was very much appreciated.
All in all a memorable experience. Can't wait to go back!