We had a great month in Silvia's apartment in Testaccio. The place is freshly renovated and very well equipped. It has a comfortable bed and the fold-out couch is good enough for a couple of nights. There is more than enough space for two people and it's still quite comfortable for three or four. There is quite a lot of storage space so it's also suitable for longer stays. The kitchen is not big but you'll find everything you need for basic cooking there. The wifi is fast and stable enough even for remote working. The flat is above quite a busy street and it can be pretty noisy in the night if you like to sleep with your window open. However, Silvia provided earplugs in case that would bother us (and you can always close the window :)). You also have an access to the roof terrace which is shared with the neighbors in the building.
The area is quite lively, full of bars and good restaurants. The neighbourhood is not too touristy but still walking distance to the city center and Trastevere. And there is the best gelateria just next door! All in all, we had a great stay and would gladly come back again.