I stayed four months in Appartment B (the smallest room in the appartment). The room is pretty small but I think it's okay and reasonable. It has a window facing the backyard, which is nice as it is probably not as loud as in the other rooms. However, the room has three disadvantages. First, the room is right next to the bathroom which is pretty loud when others take a shower. Second, the window wasn't very well insulated. So, in winter it was pretty cold in the room (13°C) and it took more than an hour for the heating to get the room to 19°C. And during the hot days it got pretty warm in the room. Third, one of the neighbors has an AC unit placed there, which is pretty loud while running (which was the case during the hot days and nights in May). I wasn't able to sleep with an open window which was bad as the room was very warm (26+°C) during those days. Also, the table in the room is very small and working there wasn't very comfortable (which is not necessarily a disadvantage depending how often one is using the table).
Overall, the appartment is in an old building and a bit run down. Due to the bad insulation it gets pretty cold in winter and pretty hot in summer. Since Sophia asks you to switch off the heating when you leave the house in winter it takes a while until it gets warm when you're back.
Nevertheless, the location is pretty good to explore Boston and Cambridge and the communication with Sophia was very good.