Our stay at Casa Marietta was amazing and the place is just as described. It's a short walk to the city centre and about 30 minutes walk to the central bus station and train station.
The place had everything we needed, towels, things to cook with, air con and wifi. The roof terrace was amazing and invites to end or begin the day relaxing there. Communication was quick and all our many questions were answered and we got lots of tips for the area!
One thing I want to say about the location, we would not recommend to walk to the beach as the walk isn't nice, better to take the bus or visit surrounding beaches South or North of Catania, which we found were nicer beaches (if this is why you visit Sicily)! We had a hire car and found it easy to explore starting from Casa Marietta.
I would absolutely recommend staying at this air bnb!