My friend and I stayed for a week in Valentina's apartment and we had a pleasant experience. The communication with Valentina was good and at the check-in her friend Christian welcomed us very kindly.
The location of the apartment is just amazing. Next to the Pantheon you're located in the center and you can walk to most of the tourist attractions. The apartment itself is very spacious for two persons. The airconditioning is working perfectly. The kitchen has all the things you'll need to cook.
The only thing we didn't really like was the contruction work in front of the building. The workers would start early, around 7 am, and that would wake us up. But of course this isn't the fault of Valentina and it's temporary.
So in general we're very happy with our stay in Rome and Valentina doesn't deserve less than 5 stars.