I stayed with my wife begining of July in Marcos flat. The flat was perfectly clean and we found everything as shown in the pictures.
The flat has all the amenities you need and the terrace was great especially in the mornings for breakfast or for a sundowner in the evening. The communication with Marco and his father was easy and they were very friendly and helpful.
When booking this you should consider two things. We were looking forward to spend some time at the beach and hoped to have direct access in front of the flat. Unfortunatly the coastline across the street was rocky and not sandy as we hoped. Across the street was a hotel or beachbar that played very loud music untill late at night on 2 days during the week.
It may be helpful to rent a car in order to be able to explore the area and get to sandy beaches. In general Mondello is quite crowded in July and August which means that the beaches are quite full.
Overall we enjoyed our stay and had a lot of fun exploring the surrounding area.