We really loved our stay at Sven's. It's one of the prettiest places we've ever stayed in, Airbnb or otherwise. There's some really nice art in the apartment, the staircase is gorgeous, and so is the terrace. The location is perfect, too. The communication was very easy, and Sven seems like a very kind man.
The only downside was that it can get quite chilly in the apartment - Sicilian houses are obviously built to repel heat, not absorb it. This one is more on us, as Sven had provided an electric heater, and the blankets in the apartment are super warm. But we recommend bringing some warm clothes and socks if you're visiting during this time of year.