Great location and great host! The studio is a 10 minute walk to the Vatican and a 10 min walk to the nearest metro (Cipro Station) which will get you to the Roman Center quickly and easily. For example, it's a 20/25 min ride to the Colloseum/Roman Forum and that's the furthest major site! Castle of Saint Angelo, Trevi Fountain, Borghese Gallery are all along the way. Best thing is that since you're just outside the city center, the neighborhood restaurant's are cheaper and just as amazing (personally recommend Bonci pizza). Also, go to the local Trionfale market if you want to try cooking your own food. Don't worry, even simple dishes will taste great with these ingredients.
Fabio was a great host. He picked us up from the airport for a modest fee (cheaper than a taxi) and explained the surrounding area. He had fruit, Italian gummy candies and a bottle of wine as a welcoming present. We locked ourselves out one day (lol) and he was there within 15 minutes to help.
The apartment itself is small but clean, perfect for a couple. It has all kitchen essentials and a washer (clothes dry on roof). The only downside is the internet can be slow. Not that big of a problem though if you're only using it in the morning /night to look up last minute things.
All in all, it was a great place that I would recommend.