We loved the apartment and the Trastevere area was a brilliant place to stay. It felt very safe, but lively and fun at the same time. Great atmosphere and visually a VERY attractive, traditional Italian architecture in the area. Lots of reasonably priced restaurants and bars, and mini-marts for groceries etc open late at night and walking distance or easy public transport to the sights of Rome. The apartment was nicely decorated and a cool haven from the heat of the summer afternoon in Rome. It was surprisingly quiet at night - we couldn't hear the noise of the restaurants etc once we were inside. The little terrace was a lovely spot for morning coffee or an aperitif in the evening (watch out for the 2 pigeons who live up high), and the kitchen was great for cooking our own meals. We had our 2 teenage children with us and were very comfortable.
Communication with our host always received an immediate response and he dealt with any issues we had straight away. When we were a bit late arriving (and our mobile phone was not working in Italy) our host's representative had waited patiently and met us at the door with the keys. She settled us into the apartment quickly and gave us lots of great advice on the area. The internet was good, although it did not reach the 2 bedrooms, but that was OK as the loungeroom and dining table were in range.
The airbnb process is brilliant - info on getting to and from the apartment from the airport was emailed and texted to me in advance. We had a fantastic 3 weeks - Guise is a wonderful host and his apartment is perfect.
Grazie mille!