We very much enjoyed staying at Walter's place. The apartment was spotlessly clean and very well equipped. Walter and his wife welcomed us and explained the apartment. They were very helpful.
The location was great for us. We particularly enjoyed that the apartment is not directly at Mondello beach. This way we could enjoy the beach, which is just a few minutes walk away, easy access to restaurants and bars, but also had the privacy of the location around us slightly away from the main tourist area.
A tip if arriving by car: Do not drive down Via Martini but use Via Calliope and drive to the end where there is a little square. Here is easy parking without having to drive through the narrow lanes. Access to Via Calliope is slightly hidden and can be easily missed. I would stay again at Walter's place.