This was a mixed experience. We had a wonderful stay at Stefania's flat, it's beautifully finished though a little impersonal, like a family suite in a four star hotel in a fantastic location – right by the Ponte Vecchio on the Oltrarno but nonetheless quiet. It's very well equipped, and I'd definitely recommend it as a place to stay.
However, a week after my return I received a request for a large sum of money to cover damages that we were (sincerely) not responsible for : a slab table top which was broken on our arrival, a stain on the sofa upholstery, which in fact we had not used as a sofa – it was made up as a bed for us on arrival and we left it that way - and a crack in a plastic lamp base, which I am certain we didn't cause. The request was very polite, but the owner didn't ask any questions, just sent an invoice for 675 euros accompanied by photos taken by the cleaner/ manager person (all check-in, cleaning etc seems to be delegated to hired staff). Most surprising, I wasn't asked to cover costs for cleaning the sofa, but to have it completely reupholstered at a price of 600 euros.
There has sadly been little dialogue around the issue, and it's left me suspicious of the cleaner at least (the table has had something heavy slammed on it, I can only think of a chair being put up on it whilst cleaning), but also of this request for reupholstery as opposed to simple cleaning, which (apart from the fact that we didn't stain the sofa!) felt a little opportunistic. This said, it was such an impersonal experience that it's difficult to build up trust on either side (I do understand that hosts put a lot at stake) or get a feel for people's motivations... Had I met Stefania face to face this post-trip exchange would doubtless have felt less brutal.
In short : definitely a great place to stay, I do recommend it, but do a full inventory of fixtures on both entering and leaving the premises (tricky if you arrive late and leave early as we did).