You can't beat this location - right in the center of Trastevere, with amazing bars and restaurants right outside your door! We loved the neighborhood, and would 100% stay in this area if we came back to Rome. We didn't take a taxi once - we walked to the Spanish Steps, to the Colosseum, to the Vatican, etc. Check-in was easy, and Antonella even helped book us an airport transfer on our way in.
I would call out that there are effectively no windows in the unit, so it's not a super pleasant place to pass an afternoon reading and drinking some wine. The basement-ness does help keep it cool if you come in the summer months, but is disorienting when you wake up to no light and can't tell what time it is. For folks like us staying for several weeks, this was unfortunate, but if you're staying for only a few nights and plan to be out and about all day, perhaps not as much of an issue. The unit also shares a wall with a restaurant, so on the weekends you'll hear the loud squeaking of chairs until it closes at midnight.