I stayed 2 weeks in December at RTS and it was a pleasure. The room was well equipped and very clean, although I found it a bit narrow for my liking. There was central heating that started in the morning and evening, which was nice as Rome can be a bit chilly in winter. The shower was a bit on the weak side, but there always was hot water, so no big deal.
Across the street there is a small restaurant that serves decent breakfasts (English and Italian style) and a delicious risotto with shellfish, should you want to dine there. 150 meters away, by the big piazza, the breakfast will cost you double. Restaurants are abundant in the area, Vecchia Roma and Krishna (Indian food) were superb!
The location of RTS is excellent with a 5 min walk to the railway station Termini and the city buses, as well as the subway. You will easily get anywhere within, or without of Rome. But Rome is wonderfully walkable, and you will reach for example the Colosseum and Villa Borghese in 30 min, the Pantheon and Fontana di Trevi in 25 (or less).
Roberto, the host, is a charming and very helpful guy! He can answer most questions a tourist might have and also sells tickets to most attractions as well as the buses.
All in all I had a very nice stay and I definitely recommend the Rome To Stay if you're looking for a nice place at a humane price.