We really enjoyed our time in Mondello and would highly recommend staying at Mariano's apartment.
The location was great - 5-10 minute walk from the beach and surrounded by some great local restaurants (which Mariano recommended) away from the more touristy beach strip.
The apartment was clean and spacious and has everything you would need.
Mariano was a great host. He went above and beyond for us and was always contactable (even at 11pm when I needed to find some medical assistance).
Overall, we had a really lovely time!