Its all about the location and convenience. And not much more than that. The place is centrally located in Alfama and is a 5 minute walk away from Martim Moniz metro station (which is also the starting point of Tram 28). It is also close to Ramiro (must visit for seafood lovers) and other good eating places. We never had the breakfast at the apartment as its not something amazing (no hot meals as one cannot cook in the apartment) and much better breakfast options are available nearby. The San Jorge castle is 15 minutes by walk. We had an early morning flight out of Lisbon and it was very easy to get an Uber at 3 AM (I had scheduled a trip in the app).
Rafael is a great host (who, mind you, does not live in the apartment) and helps with all the questions you post. He visits the place for restocking and welcoming guests. He says the place needs some renovation and I could not see myself disagreeing with that. The pictures on the listing are definitely old at this point and the cracks on the wall are very obvious. The mattress could have been better. It is located in an older part of Lisbon and it reflects on the apartment.
It is a fine place if you have a short stay of a few days. I would suggest looking elsewhere in Alfama for longer stays.
Would I stay again in the apartment - Probably not.
Would I stay again if the place is renovated - Yes.
Would I recommend Alfama as a place to stay for tourists - Absolutely!