I stayed here for the month of August and it was great. Ivana arranged airport pickup which was super helpful. I'd highly recommend this. Apartment is clean. No a/c and I was there during an August heat wave and the apartment is still comfortable. Window facing the street has bars over it so it's very safe to leave the window open. The other windows face a courtyard. Most of the people who live in the building seem to be older and very friendly. Wall are very solid and you don't hear much noise from the neighbors.
There's a small washing machine and a clothes line outside or a folding rack inside for wash. If you're in a hurry there's a laundromat about 5 minutes away by foot.
Other reviews mention the restaurant across the street being noisy. Who cares? It's Italy. It's not like it's a disco or a place with a bunch of riff raff. I actually like the fact that there's a busy restaurant right outside the window. And the food there is incredible and cheap.
Testaccio is a nice neighborhood - I went in August and many things were closed which made it feel a little lonely but never unsafe. Walked around at all times of day and night and didn't have any problems.
Easy to take a bus to Trastevere and the main sights. The scooters like Lime are also a great way to get around.
I will try to stay here next time I come to Rome.