Mario E Simona were very responsive and it is very easy to get in touch with them.
The apartment is nice, spacious and clean.
If you are planning to stay there during the colder season, you should know that there is just an A.C. in the bedroom and it's pretty cold in the rest of the apartment. We were there working the during day and it was pretty hard due to the fact that it was very cold in the living room. To be quite fair, we asked for a radiator and they did offer to provide for one, we just didn't want it anymore.
Sometimes it's loud late in the evening, but I guess this how the streets are in Palermo, nothing to do with the apartment.
Also, the internet/wi-fi is slow (but I don't know whether this is normal there or not).