Overall, we had a great stay at Stefano and Elena's apartment. It was a perfect location for seeing the sights in Florence. Elena was very helpful being there to grant us an early check-in, show us around the apartment and point us in the direction of relevant sights.
The only issue we had was the amount of hot water for the shower. My wife and I each had a cold shower after going second on different days. I'm not sure if the hot water source is shared elsewhere in the building and we just had bad timing, but that was a little unpleasant. It might really just be our expectations are different as Americans as we had similar complaints at 2 of 3 of our other hotel/airbnb stays in Italy, so take my complaint with a grain of salt.
Regardless, I'd still highly recommend this apartment for any singles or a couple visiting Florence and would definitely look to stay here again if we were going back.