Marco's apartment is in an amazing location in Trastevere with easy access to the rest of Rome's city center. Marco was very kind and arranged a driver to meet us at the airport and he took us straight to the front door in less than 40 minutes for 55 euros. This is about the same price you'd pay an uber or taxi, so that was nice of him to arrange and made our arrival very carefree. You can alternatively take a train for 8 euro to Trastevere station and then a bus for 2 euro, but that will take twice as long and is just not worth the hassle if you can afford the private transfer. He will also take you back to the airport at the end of your trip if you wish.
Marco met us at the apartment and showed us everything we'll need, including a list of recommended restaurants, gelato shops, and things to see/do around Rome. He was very responsive and quick to answer all communications. The apartment was extremely clean and he had everything we needed including towels, soap, a full kitchen, washing machine for clothes (you have to dry on a heating rack), and fast WiFi.
The place is the perfect size for 2 guests, but you could get away with 3-4 if one or two of the guests don't mind sleeping in the living room on a pullout couch. For two couples, it was a bit intimate because there's only one bathroom and it's in the bedroom, so whoever sleeps in the living room has to go in the bedroom to use the bathroom.
The only other thing I would recommend is that you run some air conditioning while you are sleeping because it tends to get a bit humid being a basement unit with only two skylight windows that open and close mechanically. This will help to dry out the air a bit.
Otherwise, we have 0 complaints and would definitely recommend Marco's place for anyone who wants to stay in Trastevere.