We really enjoyed our stay in the flat. It is in an absolutely perfect location for all sightseeing. You do not need a car. Public transit is super close and reasonably priced. We took the metro from the airport (with only one change at Alameda) to a stop which is only a couple blocks from the flat. Antonio, who let us into the flat and showed us around, was lovely and super responsive when we reached out during the stay.
One problem with the flat for us was no ventilation in the bathrooms. One bathroom had a window that we could open, which helped, but the other did not. We got some pretty strong sewer smells. It's also a bit smaller than the photos indicate, but we were out most of our time there sightseeing, so that wasn't a problem.