First off, the owners are wonderful. The communication was excellent from the minute I booked the apartment. They arranged drivers to and from the airport and had someone at the apartment to give us the keys and show us around. This was our first time to Rome, so that was very helpful!
The apartment itself is spacious and clean. It has 2 large bedrooms, with comfortable beds. The kitchen is small, but it has everything you need, including a washer/dryer. The bathroom is also small, but adequate. The ceiling in the bathroom is rather low, so if you're taller than 6 foot, you may need to watch your head.
The best thing about the apartment is the location. It is just across the bridge from central Rome. We we within a 20-30 minute walk to everything we wanted to see. Trastevere itself is a fun, colorful neighborhood, with excellent restaurants and nightlife.
Lastly, don't rent a car in Rome. There is little-no parking, and the streets are very narrow and crowded. You won't need one staying at this apartment. If necessary, there is a taxi stand close by.