My friends and I stayed here for two nights while we were in Florence for a wedding. It is in a fantastic location right in the centre, in walking distance of the local sights, such as Duomo, Uffizi Gallery etc.
The apartment itself is spacious and stylish, with a downstairs kitchen/living area and bathroom (including shower) and then upstairs there is a twin/double room, a small single room and another bathroom with a shower. The sofa in the living room also folds out into a sofa bed. There is air conditioning in all the rooms, however, we didn't use it as we never felt that the apartment got too hot.
We didn't spend a lot of time in the apartment as we wanted to explore the city and also were at a wedding on the second day, but it was a great base to return to and we couldn't fault the location.
It's worth noting that the apartment is located on the second floor, with no lift, so there's quite a lot of stairs to climb. This was not a problem for us, but perhaps could be an issue if someone in your party struggles climbing stairs or if you have small children etc.