Carlo's flat is right in the middle of the excitement! Campo del Fiori has lots of great restaurants and is within walking distance of most sights in Rome. The other side of that coin is that you can hear the drunken conversations of those standing outside the bar on the corner when you're trying to sleep. Bring earplugs or go join the drunks because it gets noisy.
When we had a problem with the shower, Carlo came over at midnight to fix it (the shower head has an OFF knob that is delicate and turned accidentally). The shower room is clean and attractive as well, but only has about 5 minutes of hot water and no proper drainage. So expect to have wet feet when you need to use the potty. I would recommend this place for 1-2 young night-lifers.