The apartment is lovely. A group of 8 of us stayed here and had a great time. There was more than enough room for everyone and the location is great.The entrance is right on the piazza campo de Fiori, so you are right on the doorstep of a square full of market stalls during the day and restaurants and bars in the evening. Walkable to the Vatican, colosseum and other landmarks. Check in was easy (there is a code for the front door and a lockbox inside containing multiple sets of keys) and the host was helpful with answering any questions we had.
I would say that on busy nights you probably will hear some noise from the piazza if you are sleeping in a room facing it, but in my eyes the window does a very good job at blocking out the majority of sound