A wonderful stay with a few caveats...
Gloria's flat is comfortable, reasonably priced, and very well located. It is easy walking distance to all of the tourist attractions, but set far enough back that you can enjoy the local flavor as well. The flat is on the ground floor, but has very secure doors. There is a lot of street noise, but that is honestly part of the charm. We loved playing cards or enjoying a meal with the front door wide open; we even had the occasional chat with a passerby. At night, I sleep with earplugs, so it was no trouble.
The flat comfortably accommodated our family of three. Though the kitchen is small, it is well equipped, and we prepared many beautiful meals there using fresh food we had bought from the local markets.
There were some drawbacks:
The apartment had very little natural light.
There were some rather serious issues with the plumbing. Part way through the trip, the toilet overflowed and backed up into the shower. The toilet was partially repaired, in that we could use it again, but we were not allowed to flush anything, not even toilet paper.
The wifi only worked about 50% of the time.
The washing machine does not work. We washed our clothes at the laundromat down the street.
All of that being said, we were very, very impressed with Gloria as a host. She was so kind and attentive. She picked us up from the airport, offered us helpful suggestions, and was available to arrange whatever we needed. This was not a stay in a flat that's managed by some remote company; Gloria lives close by and was available to us any time by phone. When there was an issue with the plumbing, Gloria was there within an hour. We left to explore for a few hours, and when we returned, the issue had been repaired by Gloria's father and father in-law, and Gloria was cleaning the bathroom for us. I would recommend this flat and Gloria as a host as an affordable option in Catania :)