I enjoyed staying in Loft Trastevere a lot.
It is a very modern, spacey and clean, two-floor apartment, best suited for a family or a couple (admittedly not so well fitted for unrelated people coming to Rome in business, as there is no clear distinction between a living space and a bathroom and sharing a shower may be quite awkward).
The apartment is located about 7 min on foot from tram line and 10-12 from the old Trastevere. There are some shops, restaurants and coffee shops nearby (in the 5-10 min range on foot). It takes about 25 min on foot to get to Piazza Navona. The public communication from Fumicino airport is also very convenient (26 min by train to Trastevere train station + 5 min tram ride + 7 min on foot).

Celeste is wary flexible and friendly. My flight was delayed over 2h, but it was no problem to contact her and re-schedule the meeting to receive the keys.