Valentina's apartment is very well located, especially when you're arriving by train. It's just a 10 minute walk from the Termini station to the apartment. Otherwise you're probably going to have to use the Metro to get to the center. But that's not a problem as the Metro station is just 3-5 minutes from the apartment. There's also a grocery store close by and an awesome gelateria just around the corner.
The apartment is not big, but very comfortable for couples. The kitchen is modern and there are all the kitchen supplies you could possibly think of.
I also want to recommend Valentina as a host. She's more than willing to help and answer all your questions.