The apartment is perfectly located a short walk from the train station and close to all the major sites with good access to the oltrarno as well. (In my opinion the best restaurants are in the oltrarno.) The check-in process is excellent because you can do it all from your phone. I had to do a bit of work during my stay and the wifi connection was strong even for video calls. You do have to make sure you tell her how many beds you want to use otherwise the other beds will not have linens.
Mary was very responsive and helpful. We are so grateful for her apartment and a great stay.