We had a great time at António's apartment. The apartment is ideally located, with a view of the harbor and plenty of light. The neighborhood is the heart of one of the highly-touristed areas, but we never felt inundated by it. It's also very easy to reach other parts of the central city, either on foot or by public transportation. From the airport it's a breeze, the nearest station being very close.
The space is very generous; in fact, it was more room than we needed (there were three of us), but it was nice to be able to spread out across the two floors. The kitchen is tricked out with just about anything you'd need, and despite the liveliness of the neighborhood, it's well insulated and quiet. The fourth-floor walk-up is not for the faint of heart, but I found easy as it's ample and well-lighted.
António was always available and responsive if we had any questions. To sum up: a wonderful time was had by all!