We had a great stay in David's apartment. It was modern, comfortable, very clean and quiet and had all the things we needed for our stay. It's in a great neighbourhood - felt very safe, even at night. It's just outside the old town but easy to walk to all the main sites and around a half an hour walk to the main train station (Firenze SMN). There's 2 large supermarkets that have everything you need about 5 minutes away.
David was really easy to communicate with and responded to any questions I had very quickly.
I'd recommend his apartment to anyone visiting Florence!