If you're spending any real time in Florence, you're pretty likely to cross the Ponte Vecchio,…read morewhich spans the Arno and more or less connects Palazzo Pitti to the Duomo. You'd walk it even if it were just any old bridge, but it is in fact The Old Bridge: a medieval stone arch bridge, and the only bridge in Florence to survive World War II.
We never made a point of visiting Ponte Vecchio, but we walked across it several times during our two days in town. It's a lovely bridge, with shops built onto both sides--I guess this was a common thing in medieval times. The shops give the bridge an interesting building block look from the outside, and form a vibrant commercial corridor within. No car traffic, but plenty of pedestrians at all times.
Most of the shops on Ponte Vecchio seem to sell gold jewelry. I recognized a few chain jewelers, but I think those were in the minority. I doubt Ponte Vecchio is the place to get a good deal on gold jewelry, but if you want a gold souvenir from Florence, it's probably worth a browse.
We didn't shop on Ponte Vecchio, but we enjoyed the bridge as a bridge, a practical monument full of beauty and history. It offers prime views of the city and is, of course, a marvel in itself. We enjoyed seeing the shops open, but the bridge was even prettier at night, when they were closed. The storefronts all had these wood shutters that made them look like treasure chests. So charming.
We were in Florence in mid-November and saw the Christmas lights go up over Ponte Vecchio but didn't stay long enough to see them turn on. I'll bet this bridge is magical during Christmas, but it's not like it isn't special all year round. It's one of the places that makes Florence Florence.