We really enjoyed our stay at Gianni's place! The flat was very spacious, we were only two people but there was comfortably room enough for 6. All the facilities we could possibly need were there, and we really loved being able to make a coffee with the Moka each morning and drink it out on the balcony. The shower was also a highlight!
The apartment is on the edge of Testaccio, with views of the river and the neighborhood at your doorstep. There were so many lovely places to eat and drink in the neighborhood that we didn't bother to venture further in the evenings. You can also hop over the bridge to Trastevere if more options are required.
We found that it is possible to walk just about everywhere in the centre, but if you don't have appropriate footwear there is a metro stop at the other side of the neighborhood, and plenty of bus options. All in all, we would absolutely recommend the flat to anyone, and will be looking to stay there again if/when we return!