We've used Airbnb several times for travel now, and Valentina's place was the nicest we've stayed at for the price. It was also very clean. The location is absolutely perfect if you are wanting to go to Vatican City (it's a 2 minute walk to the entrance for the Vatican/Sistine chapel museum), although it isn't central to the rest of the major sights in Rome (Pantheon, Piazza Novanna, Colosseum etc). Take a cab and you'll be fine.
Our flight was delayed getting into Rome and we had challenges with our cell phone, but Valentina went above and beyond to communicate with us and help us get checked in. This was probably the most communication we've had with a host, but in our situation as tourists to a foreign country it was absolutely necessary. We recommend staying here.