The location can't be beat. You can walk to must major sites in minutes. We literally never used a cab or train to see all the major sites around town, but then we like to walk and explore towns. The unit is just over a block from Navona and a few more to the Pantheon. It is well furnished with decently fast wifi service(important in these days).
When folks say the stairs are steep, they ain't kidding. But it's only a few. Our only issue is the upstairs lady wears hard-heeled shoes _always_. Starting at 6am she's apparently practicing for the latest Dutch Riverdance in a pair of wooden clogs. She's out the door by 0730 but back again for a couple hours in the afternoon for riposo. In the evenings she quiets up around 10pm. If you want to ensure a good night's sleep, bring earplugs.
We'd stay with Federico again in a heartbeat. The place is so convenient.