As many have said, the location is ideal! Michele was a perfect host, answering questions and queries quickly and thoroughly. The flat is well laid out and very quiet. The only slightly down side could be that the bathroom is on the small side, so that it becomes a 'wetroom' after a shower, and any non-standard needs would be a bit difficult to accomodate (for example, bathing a child or a taller than average person showering). But the flat is otherwise very functional and enjoyable and well served by buses and trams. Michele also provided us with tips and a list of his favourites, which was a nice personal touch!
Our tips to other visitors: there is a supermarket on Viale Trastevere (one floor down) at corner of Via di San Francesco a Ripa (along which there is also nice food shopping in specialty shops). Best cookies ever to be had at Via della Luce 21 in a bakery called Biscottificio Innocenti (no sign outside!)