The place is very spacious and clean, and situated at the heart of the city with the main sights like the cathedral, the palace and major pedestrian streets just minutes away. Tons of restaurants at your doorstep and about 20 minutes walk from the train and bus stations.
Guests should be aware that, even with the double glazed windows, it can be quite noisy, particularly on nights at the weekend when there are many people and traffic in the streets. As a result in the warmer months the air conditioning (or at least fans) are a necessity. One of our air conditioners didn't work and wasn't fixed in the 3 nights we were there, though after some "coaxing" Gabriele did ultimately provide fans for that room.
The Internet was didn't reach into several areas in the multiple rooms and since there were only 3 sets of keys (for 8 people) a certain amount of coordination with the group was required. Gabriele did promise more but he never returned and they didn't materialize.
As with many old buildings the plumbing was an issue, particularly the drainage in the showers requiring a careful calibration of the amount of water used so as not to overflow.
The apartment is in the ZTL (restricted traffic zone) so if you are driving into Palermo you'll either have to pay the fee (€6 per day) or park outside the zone and walk in. It being Palermo you should probably opt for a secure, covered garage though we left our cars outside in a parking lot by the bus station for a few days without incident.
Gabriele wasn't quite as responsive as we would have liked with the various issues but the place itself is clean and ideally located, as long as you are willing to deal with the noise.