Roberto's apartment is in a VERY good location. My girlfriend and I did not take public transit at all, the longest walk was to Vatican City, maybe 30 minutes. Spanish Steps are super close, as well as a lot of other famous sights.
The apartment was great, outfitted with AC which is a huge plus. We did not use the kitchen, so I can't comment on that. The bed was nice and comfortable, as well as the living room area.
The only negative I can point out is the Wi-Fi, its a bit spotty, but nothing to really complain about. It's usable when you need it.
Roberto is an excellent host, he allowed us to drop off our bags early, gave us information, and even called us a cab back to the airport.
I highly reccomend!