We stayed for 5 nights holiday. Clean, well furnished and equipped modern apartment with the bonus of private terrace that gets the evening sun. The apartment is in a quiet residential area about 20 minutes pleasant walk along the bank of the Arno into the centre of Florence. There is a supermarket (Tuodi) 3 minutes walk away. This was so convenient and the apartment so nice that we made dinner there 2 nights, despite our original plan to eat out every night.
The apartment looks out on the magnificent new opera house and we got some last minute tickets for an opera one night, which was great and significantly cheaper than Covent Garden. Without going into the opera house you can get on to the roof for a view of Florence.
As long as you don't mind the walk into the centre, which we didn't, and in fact actually enjoyed, I doubt there are many better places to stay.