For a three-person family visiting Rome for the first time, this was a remarkably convenient, central location for home base during our stay. The unit was clean and spacious, and both excellent restaurants and convenient mini-markets were easily accessed on foot. Guido was very responsive as a host: he had a repairman there within hours, when I mentioned on our second day that there was something odd about the behavior of the hot water heater, and it was fixed before
The street access to the unit is in an alley (Arco di Santa Margherita) that is too tight for cars, but is just a few steps from where the taxis can drop you off and pick you up. The alley itself had a fair quantity of graffiti on the walls, which initially made me pretty nervous, as similar quantities of graffiti in my home city of Seattle would generally indicate a dangerous neighborhood. However, after four days using this location as home base, I came to realize that (a) graffiti is everywhere in Rome and (b) the neighborhood appeared to be perfectly safe. The most "dangerous" people I ran into were the restaurateurs in Campo de Fiori, who aggressively tried to convince us to eat and drink in their restaurants every time we walked through the square. At first it freaked me out that they immediately knew I was American, immediately addressing me in English, but after a couple days I just laughed when they offered me a seat and a menu, and replied "The answer is still no".
Speaking of restaurants, we have a celiac in our family, and the gluten free dining options in the area were AMAZING. At the high end, the seafood restaurant Assunta Madre was delicious. I was very impressed when our waiter nearly slapped my hand when I tried to share something with my wife that she should not eat. Other GF winners included Mama Eat (100% GF menu), and Pizza in Trevi.
Overall, I would recommend this unit to anyone touring downtown Rome. Just bring comfortable walking shoes.