Marco's place is great. I stayed there for 9 nights with my girlfriend and we loved the place. I travel to Rome often to visit friends from my university days and this has been the best Airbnb I have stayed at in the last few years. We were met by his father for check-in who was very helpful and did a great job showing us around the apartment so that we would know how everything worked (i.e. stove/oven, making sure the hot water heater stayed on). The location is excellent. The apartment's location is steps away from the best restaurants and nightlife in the neighborhood but is on a quiet street so you don't have to keep hearing the party after you decide to turn in for the night. In my opinion it is very walkable to everywhere you would want to go if you are fit and willing.
Otherwise, it is very close to the tram that runs across the river to the city center and a cab stand. We opted for the pick-up/drop-off from FCO service Marco has as an option in his listing. With the cost of a cab to and from FCO being 48 euros each way the service is well worth the couple of extra euros to have a private driver. The place was clean and well represented by the photos. There was ample space for two people to store their belongings for a 9 night stay. The mattress is very comfortable but the pillows are a bit thin and probably need to get replaced in the near future. The apartment has ample linens for 2 people. The bathroom is nice. The shower has really good pressure, and as long as you remember to not hit the switch that controls the hot water thank, you will have plenty of hot water. The kitchen is small but is open to the living room so there was plenty of prep space with the large dining table. There were ample plates, cups, mugs, wine glasses, etc. as well as everything we needed to cook a few meals although we ate out most of the time. The wifi signal is good in the living room/kitchen but poor in the bedroom. I would recommend Marco gets a booster that plugs into one of the electrical sockets to get a better signal to the whole apartment. Overall we had a great stay at Marco's and will definitely be looking to see if it is free the next time we travel to Rome to visit our friends!