I did not quite realise what we were getting with this b&b until I arrived. A bit unexpected but I loved it! You are basically living in a room which is part of a few joined-up flats in a period building on the south side of river Arno, a few hundred metres down the road from Ponte Santa Trinita, around the corner from Palazzo Pitti and close to Basilica di Santo Spirito. You are right there, in the middle of it - and every night you open a heavy door with your key, go up old worn steps to the 3rd floor (no lift of course, as you are in a different century) and disappear behind an oak door.
Each room has its own colour, is spacious - but the only new piece is the ensuite bathroom facilities (even the wardrobe is old and creaks). You get assigned one of the breakfast tables, can operate the espresso machine to get coffee and get the cold cuts, yoghurts and juices from the fridge (along with any stuff you want to buy and store - that's fine as well). All of this is explained to you by the super-friendly Elisabetta, who can also help you out with some travel tips. One detail: my wife arrived well after midnight, so we slept in quite drastically the following morning - yet Elisabetta was quite happy to help us out with the now brunch, as all the food designated for us was still there, waiting for us in the fridge. So you get complete autonomy, with some help from the owner wherever you need it.
Highly recommended if you want an alternative to a traditional hotel stay - this is also traditional, but in a different and fun way, it is like actually living in Florence for a few days!