Excellent place! The apartment was clean (most important of all), modern, and had a fridge stocked with supplies (added bonus).
Out of 10, I would give the place a 9. The only reason to lose one star is because the AC unit is upstairs, while the beds are downstairs. We were there in July with mid 90s temperatures, and nighttime was bearable downstairs. That is the only complaint. Otherwise, the place was absolutely fantastic.
As for location, I have mixed feelings. Trasvestere is definitely the best neighborhood for getting away from tourists and being around locals. It also has the best restaurants and bars in town. If I were going to Rome purely for food and fun, I would stay at the apartment and couldn't choose a better place. And Rita's place is in the center of Trastevere, walking distance to everything in the area. The downside is the distance from all the sites and lack of transportation. If you're planning on walking everywhere, then you are all set. The train station is a few miles away, as is the Vatican. And the only public transportation is one tram (#8) and a few busses (which are practically impossible to figure out...I know bus H goes by). But the Metro is nowhere near.
So, to recap, an excellent place. Great food and nightlife close by, and away from tourists. But not great if you plan on using public transportation.
By the way, Rita is an awesome host. She responded to any questions I had within 5 minutes and had beer and wine for us when we got there.