The apartment is lovely and we really enjoyed our stay, it is in a perfect location with a good kitchen and a supermarket two doors away...... there are also plenty of cafés and restaurants in the street and surrounding area.
As in any busy city and popular tourist location it is noisy at night but that is the pay off for being 50 metres from the Duomo complex. We were there over Easter and got to experience the 'Explosion of the Cart' first hand, would have been much harder staying elsewhere. You wake to the ringing of the bells from Giotto's Bell Tower, an experience in itself!
Unfortunately the lift was locked for the first floor and we had to carry our cases up and down two flights of stairs, In normal circumstances you still have to climb one flight as the lift does not reach the ground floor - in my experience this is not unusual in old European cities but can be an issue for some people.
Don't hesitate, once the secret is out you will be queuing up to book this apartment ;0)