Roberto's apartment is a seriously cool place to base yourself in Rome. The unit is on the 1st floor, but there is a small lift to handle the luggage, the place is bigger than expected, the shower is good and the bed wonderful (just what a +60 year old traveller needs after a 32 hour flight from Australia)
Across the road is a small coffee kiosk with excellent coffee and selections of breakfast croissants and sandwiches. Saint Peters & Vatican is an easy 10 minute stroll away and all the Hop-on Hop-off buses pass nearby. Ask Roberto to recommend some restaurants around Trastevere as the place is restaurants and bars wall to wall along the little alleys and streets. Plenty of scope if you're on a budget as well. We dined at home one night and the kitchen is well equipped!
Strongly suggest you research getting a Roma Card for free bus/tram/train travel and VIP access to main sites eg Colosseum, straight thru bypassing a 40 minute queue. We also bought the OmniPass which for Eu$8 pp extra includes the 2 hour Vatican Tour and we walked straight past a 600metre line there also.
Roberto's was spotless, well equipped and we have already recommended it to other friends travelling Europe.