Francesca's place is immaculate in terms of cleanliness and attentiveness to her guests' needs. We communicated easily, and she lives right across the hall if any problems arise. When the internet went out, she reset it within minutes. There are ample supplies for cooking, and more than enough sheets, towels, and blankets.
In terms of location the apartment is very convenient: 5 minutes' walk to the Accademia (David), Santa Croce, and the Duomo. You can also get a number of buses at Piazza San Marco, which is less than ten minutes away. It's also very close to the Sant'Ambrogio market and lots of great restaurants in Santa Croce.
The only weakness of the apartment is that it does not get a lot of natural light, but I think this kept the place cool--even when it was very warm during the day I didn't need the air conditioner at night. And besides, you're supposed to be out seeing the city!