Dario's place was great, perfectly located between walkable (The Forum and Colosseum) and quiet (away from the noisy, tourist heavy locations). It's also an easy 5 minute walk from the metro line that takes you to Termini Station, the Spanish Steps, or St. Peter's Square.
Dario (and his coworker Andy) were very helpful with our check-in, as there was a transit employee strike the say we arrived and the city was in chaos. Dario gave us tips and was in frequent contact during our arrival, while Andy stayed later than expected to greet us due to apocalyptic traffic conditions.
The apartment itself had every required amenity and a variety of lighting/cooling options for those who are more choosy. Dario's suggestions for travel and food (Luzzi in the Colosseum district, though reservations down there are basically required) were spot on and he was conveniently located to several other good restaurants (Rigatoni right around the corner) and gelato (Fassi, OMG!!).
We stayed for 4 nights and would definitely recommend Dario's for anyone visiting Rome!