The location is excellent, not far away from the train or bus station. Really close to all the museums and cathedrals in Florence, has a lot of restaurants and grocery stores nearby.
The apartment is in good condition, on the last floor of a historic building in the city center. May be kind of hot in the summer, but it has air-conditioning, so it's fine.
Regarding the cons - the street is a bit noisy, but if you close the windows, it's not a problem.
The hosts are great guys, helped us out each time we asked for an advice, made a nice intro to the city's interesting places. Most importantly, gave us the possibility to make a late check-out / leave our luggage for a while in the room.