The location, in Piazza della Signoria, is right in the center of things and we loved it. A 10 minute walk from just about every place in Florence.
The apartment is quite unusual: large and airy, with 15(?) foot ceilings, filled with artwork just as the name suggests, a fully modern kitchen, comfortable to hang out in or to use as a home base. We enjoyed cooking some of our meals there, eating others out.
Just like other reviews stated, the apartment is very noisy, especially at night. We used a white noise app on our mobile phones and we were fine; we would have been unhappy without them.
We were surprised to find all 3 bathrooms in one central location, all right next to each other. It didn't make for the best feeling privacy, unfortunately.
We had a wonderful time in Florence and would happily stay in Stefano's apartment again.