Overall the experience was great - one minor issue with WiFi that I will describe at the end.
Mariella and her husband are very friendly. We arrived at 10:30pm (22:30) on Wednesday evening and she was gracious and flexible with us with the late check-in. Mariella lives around the corner from the apartment. The apartment itself is beautiful. It's an old building perfectly situated to explore the Ortigia area of Syracuse - you really can't beat the central location. The old building has so much charm while the interior of the apartment is crisp and fully renovated, with beautiful new wood floors, high ceilings, several balconies overlooking the pedestrian streets below, and tastefully decorated (with what seemed like an IKEA collection). For just the two of us it was quite large. A generous bedroom, a large living room, and a small kitchen nook by the entry. The apartment is very clean. We were lucky to find street parking around the corner.
The only small issue we had was with WiFi: I was only able to connect with my laptop in the living room. We could not get our iPhones to detect the signal from anywhere in the apartment. We were lucky to be traveling with a laptop. Otherwise, this would have been a troublesome inconvenience. As foreign travelers, we usually rely on having a solid WiFi connection wherever we stay, and that was not exactly the case here. This was my only criticism of the experience, otherwise wonderful!