We stayed for 2 weeks. The apartment was very clean and next to Trevi Fountain. We were able to go out early in the morning and have it to ourselves before all the other tourists swarmed it.
The layout with the split rooms was great. The internet was high speed and worked everywhere. The kitchen was well stocked. There's a grocery store 3 mins away and a ton of restaurants and gelaterias (super impt!) all within minutes of the location. The host was great and responsive. The elevator was quick and always available. EVERYTHING was only a 20 min walk from the apt.
As others have noted, there is a lot of outside noise due to the (great) location. The windows do a good job of lowering it to just a dull murmur. I'm not sure if it would be any quieter at any other similarly amazing location. We came with a toddler and although the noise possibly seemed to affect her sleep, everything else about the apt/location was so perfect that we both agreed that we'd still stay there again.