We had an ok-ish stay at Leonardi apartments. We selected this apartment because it listed Heating in the amenities list. However, when we arrived, we were told that the apartment will turn on the heating only from December onwards. During the night the apartment cooled down quite a lot (no much of insulation) and it took some fortitude to go shower in the morning!
Location is great and I can imagine in warmer months the apartment is OK, but for colder months, before the heating, I will not recommend it.
The guide and reception were really great though, and it has a good location to explore Catania.