Located basically opposite of Termini Station, where it is consider a main hub for local bus,airport-express,inter-city trains.
Near to alot of eateries, and even the Termini Station itself is a little small shopping hub by itself.
The room is clean, and spacious. The host is very friendly and though the breakfast served is simple, but is really good. It's located on the first floor of a building, so is either you can take a lift or walk up.
You might want to check for the exact location through google maps, as I arrive at Rome from the airport directly through train, and exit at a further exit door, and end up detour slightly to find the place. Bring together with you a map to show direction from Termini Station to the B&B at least. Once you reach there, the host will give you a local Rome map which is really useful.