An overall solid stay.
The plusses...
Location: Campo de' Fiori & Jewish Ghetto (5 mins); Trastevere & Piazza Navona (10 mins). Everything else is central as well. Hard to imagine a better spot than this one. There's a Coop market 3 mins in one direction and a Carrefour equally close in the other direction.
Apartment: So spacious. Two true bedrooms, good closets. Well appointed kitchen, proper dining area. City apartments are rarely so roomy/functional. This apartment stands out in that regard.
Communication: Host was very responsive whenever we had a question or issue.
The minuses...
Infrastructure: it's an old building, and the electricity and plumbing reflect that (eg: can't use all appliances simultaneously). Once you get the hang of the place, it all works -- but it can take some trial and error.