Giulia's apartment is very charming. It is very spacious and well furnished. We were pleasantly surprised at how much room we had to spread out compared to the place we stayed at in Rome. Guilia has also done a very good job decorating this space, and making it feel like a home. The terrace is also very lovely, and has a great view, although my wife and I were not able to use it much since the weather was rainy and cold during the first half of our stay.
The location is decent, with around a 10 minute walk to the Duomo. It is also only a short walk from several of the major bus routes. There are many small shops and restaurants nearby, including a nice bakery just across the street. There is also an open market just a block away. There are more central areas you could stay in Florence, but this area worked well for us.
This location is on the top floor (4th floor), and is only accessible by stairs. My wife and I enjoyed being on the top floor, but if stairs are a challenge for you then this would be a downside.
Giulia was also very good host. She met us at the apartment for our check in, and went over the details of the apartment. She even left us a bottle of wine to enjoy on the terrace. If we are able to return to Florence in the near future, we will definitely look into staying here again.