Great apartment and great location!
Testaccio is definitely an overlooked neighbourhood. Only once we arrived we realised we were situated on the same street as two of the best rated restaurants in Rome. We also had an amazing and authentic breakfast every morning at a pasticceria within walking distance too. 20 minute walk to areas such as Monti and Trastevere, both beautiful, or an easy and efficient bus service, there is a bus stop a 2 minute walk from the apartment.
The apartment complex felt very safe and well enclosed behind a set of gates, we received a warm welcome and the apartment was very clean and looked as described. Our only criticism was that the bathroom became quite smelly after showering, think there must have been an issue with the drains, but this was a minor problem and I am sure it will be dealt with.