From a value standpoint, you simple cannot beat Paola's quaint little apartment. We are doing some extended travel, so budget is critical, and Paola's place was one of the few options that we found in Florence that was an entire unit and centrally located.
The apartment itself is more spacious than we expected, with the sofa bed in a separate living area from the kitchen and small dining table. The bed was comfortable enough, though we struggled with the pillows and had to fold them up to get them to our liking. Although there isn't air conditioning, we managed by closing the windows and shutters during the day and then running the fan while we slept. The only downfall for our experience is the washer machine door was broken by the guests right before us, so we weren't able to do laundry.
If this is your first time to Florence, you will love the location. It's 2 blocks off the Ponte Vecchio on a quiet side street, so you get the best of both words (accessibility and tranquility).
Paola and her husband were also lovely hosts and he met us to get us checked in. They were clear and responsive with communication and made us feel perfectly welcome!