We were fortunate to visit here twice, both times making sunset and then nightfall. I would encourage everyone to try and do this atleast once, there are no words that can really do it justice. This is a classic 'must experience for yourself' moment.
The walk up from the Oltrarno side of the Ponte Vecchio is steep but rewarding with two routes - we went up past Negroni bar taking the road, and down taking the steps around Viale G Poggi. At the top, along with a bronze reproduction of David, are a number of souvenier stalls and vans selling cold drinks, beer, prosecco and ice cream. A beer and prosecco cost E8 which was fair, however second visit we brought our own and sat on the steps near David taking in the view.
Bus No12 and No13 are options if the walk is to much or the weather against you however you get there though, this is imo 'the must do' regarding Florence, there infront of you is the countryside, Pitti Palace, Arno, Ponte Vecchio, Duomo, Palazzo Vechio, Santa Croce, the stadio and Fiesole and everything else in between before you.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.