After texting her from the airport, our host was waiting at the door when we arrived, and check-in couldn't have been smoother. The flat was exactly as described. The location just south of the Arno is wonderful; walking distance to all the places we wanted to visit (including the beaver building a dam at the base of one of the piers of the nearby bridge).
Every morning we'd get croissant from the bakery next door; sometimes I'd be back upstairs in under two minutes! If the weather was nice, we would sit on the balcony overlooking the busy street below, with a view of the Arno. The gelateria on the corner is a neighborhood favorite. There is an ATM and mini-market across the street, and a Conad grocery is two blocks away. One bus stop is right in front of the flat, and another is on the corner, so it was very easy to get around by bus (after downloading the ataf (bus company) app). We had a great time exploring the neighborhood, with its many artisans' shops, antique stores and restaurants. Even after our ten day stay, we feel we just scratched the surface of living in this wonderful neighborhood.
Despite being on a busy street, we had no issues with noise in the flat; we would occasionally hear the upstairs neighbors walking around, just like any other flat we've ever stayed in, and the few neighbors we saw on the steps were all friendly.