My stay at Fran's place was pretty good. The apartment is quite central because Lisbon is a very walkable city. It's actually not super convenient in terms of access to public transportation, so bare this in mind when arriving with luggage. That being said, once you're settled in, you'll probably be walking a good deal anyway.
The room itself is definitely on the small side -- It does get amazing light, though, which was probably what made the room look so nice in the photos. All in all it's perfectly fine for a short stay for one person.
Kitchen and bathrooms were all super clean and in great condition -- top marks for that.
I never met Fran himself, as he had delegated check-in to his very sweet housekeeper, Diana. She's lovely and polite, but be aware that she does not speak English particularly fluently. This sure as hell isn't her problem, but since Fran is running the rental as more of a guesthouse than a home-share experience, I think it's incumbent upon him to think a bit more professionally about things like these. It was especially difficult for the housekeeper to explain how the keys worked, and we even had to switch over to a different pair, which never fully worked properly. The doors are old and the keys are a pain to use. Again, I don't fault Diana, nor do I fault the age of the building. These variables are part of travelling. But, like I said, when an airbnb host is not present at the rental site and is choosing to rent a space like a guesthouse, they're clearly in it for the money and not a cultural exchange. That's fine! I respect that, and if this is your business, treat it accordingly.