If you are looking for a nice and cosy place to stay in Florence, stop here, you have already found it.
As an experienced traveler, I would say that Carmine is the best of the bestest hosts I ever had. Flexible, friendly, always welcoming, knowledgeable - everything you need. The place itself is just awesome- always clean and tidy, well-equipped, spacy. Although Florence is not a big city, the location of the apartments is central, all the main attractions, restaurants, and shops are walkable.
If there was an opportunity, I would rate it 10 out of 5.