I second everything other travellers have mentioned about staying with Manuela and her family. The neighbourhood is quiet and authentic, the house is 5 mins walk (maximum) from the tram and 24hr supermarket, and the tram is a short, easy journey into the centre (Termini station, from which a number of major sites are within walking distance). The street itself has two very good, very authentic restaurants, one fish/seafood, the other traditional Roman, where both the food and house wine (really!) were excellent. Also very well situated for reaching the Via Appia Antica, which is gorgeous.
The room is clean, comfortable, tastefully decorated, has an ensuite shower room and WC, and direct access to the garden (with a separate terrace and table etc - it was lovely, and not yet in full bloom). A generous breakfast was also provided daily, and plenty of advice and information for our stay in Rome. Manuela speaks excellent English and French and communicating was natural and easy.
This is the first time I have ever taken a room in somebody's house with Airbnb, and had never thought that I would want to stay with strangers in their home. I have no regrets. I made the decision to stay with Manuela and her family for two reasons, a) budget and b) to relieve us from the intensity of travelling with a small child (my son is 2) by giving my husband and I some other adults to communicate with! Manuela and her family provided the warmest welcome, with no awkwardness, a perfect balance between respecting each other's rhythm and personal space and taking time to chat. They were astonishingly lovely with my little boy, who is still dragging boxes around at home, pretending they are wheely cases and announcing that he's getting on the plane to see Manuela. I wish we could have stayed for longer.
I would also like to say that my son, with whom we travel quite a bit, is not a natural sleeper, and never sleeps through the night away from home. At Manuela's house, he slept. This speaks volumes of our hosts' kindness and humanity, and what a loving environment their home is.
Highly recommended.