Excellent experience. Location is superb - literally meters away from the office where you pick up the reserved tickets for the Uffizi Gallery/Museum. There are lots of good local eateries. Noise level is low. You do hear some noise on Friday/Saturday night but it's not very much considering where you are.
Apartment is spacious with plenty of room for 2 people for a long stay or 4 people for a medium stay. There is plenty of storage space for clothing and other stuff in the main bedroom.
Many of the other major sites are an easy walk - typically 5 minutes or less. This includes the Duomo, Ponte Vecchio, Palazzo Vecchio, Orsanmichele, Uffizi, and many others.
Because full size buses do not go into the old section of Florence, I'd recommend taking a taxi if you have lots of luggage and you're coming from the train station. We took a taxi and the cost was less than 20 Euros. We had a problem getting a taxi to take us to the train station when we left. Even with large bags, we were able to get to the SMN train station in less than 20 minutes on foot.
Good grocery shopping is about 400 meters away just on the other side of the Ponte Vechhio.
The kitchen is good basic (lacks microwave) but you can cook every meal as long as you're smart about how to do things.
The stairs are narrow, this is not recommended for people with mobility problems.