I was a bit nervous as this was our first AirBnB experience. Everything exceeded our expectations. The apartment was perfect for us and we had a delightful time in Rome. The apartment was clean, nicely furnished, and had plenty of space. The manager met us, explained everything, gave us a map and told us how to get where we wanted to go, and made sure we had her phone number. (She also spoke perfect English). We had no problem with the noise - but we were there in February when it was quite cold and we had to close the outer shutters which cut the noise. Even still, I'm a light sleeper and the traffic noises didn't bother me.
We met the owners - a delightful couple who live nearby.
Must mention the charming elevator - an old cage-style lift with wooden inner doors and a metal outer door - holds only 4 people and jerks a bit with each stop, but it's beautiful (and works perfectly).