Lots of charm. Without having verified this, I'd say the building is from the 18th century. (The sink, floor, and door are definitely not modern.) (Responding to one other reviewer, there are no cleanliness issues; the fact is that the building is centuries old. It is not dirty.) It's also been nicely renovated and modernized making for a charming contrast of character.
Location is in a quiet neighborhood on a small street bordering the Arno River four bridges downstream from the central Ponte Vecchio. Across the river (accessible via a nearby bridge) is the beginning of the Cascine nature park.
My only critique is that it is not centrally located. While just on edge of the historic center, it's a 20-minute walk (with our pre-schooler, more than that). I understand there is a tram stop (by the Cascine park), three stops into town, but we opted to walk or Uber. Also regarding location, my only other small critique is that there are not a lot of eateries or grocery stores in area.
Other than two little issues, it's a great bargain: excellent value, and I would highly recommend.