The location is great: 8-10 minutes walk from San Giovanni Metro station and bus hub, 20-25 minutes walk from the Colosseum and the old city center. It is far enough from the tourist crowd, much less tourists, so the shops and restaurants are serving locals (long term business, better attitude). Great ice cream and restaurants around (just rely on Massimiliano's recommendations and enjoy making your own discoveries). Via Britannia is a bit busy road, with significant traffic, but you cannot expect to find any less noisy streets in the city center of Rome. All the windows are facing the street. Expect to wake up at 8 o'clock in the morning - which is fine if you are there to hit the streets and discover Rome, not staying in bed too late.
The apartment is nice, the building is in good shape, residential. You may expect a bit more upscale interior after seeing the photos, but it is still fine. Everything is clean. Wifi is steady and fast. Bathroom is a bit small, but OK. For the 2 of us, it was all good, but I am happy that I did not need to sleep in the living room, since it has no doors, so the entrance is close and you may hear the noise of the fridge from the kitchen (no doors neither). The bed in the bedroom (with doors!) was also a bit soft for my taste, but that just might be optimal for someone else. So the apartment is good for a couple, maybe a bit problematic for 4 guests (there are 4 beds to stay, but not the same quality). We had a great time there and Massimiliano was always available online and responded very fast. I recommend this place if you wish to be close to the center but prefer to stay in an area that is more reasonably priced and less crowded. The place is clean and modern, got everything you need for a convenient vacation. Enjoy!