My friend and I were doing a eurotrip and Rome was the first city in which we decided to stay at a B&B rather than a hotel. The setup here is that we were renting a room in an apartment owned by a couple Pierpaolo & Julia. They were lovely and really helpful. We had our own key and could come and go as we pleased. The "breakfast" part of the bed and breakfast was a kitchen stocked with toast, spreads, milk, juices, croissants etc. That was good as everyone has different meal times. The only issue we had was the water pump which made a really funny noise when we'd turn the taps on. It caught us by surprise everytime and it was pretty loud. The apartment has no elevators so we had to carry our 20kg suitcases up and down the three flights of stairs which wasnt pleasant. Location-wise, we were within walking distance of the vatican and we found some nice places to eat in the area.
Seeing as it's a bed & breakfast, we weren't expecting any housekeeping and although the sheets weren't changed during out three night stay we were pleasantly surprised to see our bins emptied and our toilet paper restocked so that was nice. The metro was very close by (Lepanto) which was handy. The street is definitely noisy as some people mentioned previously. I'm usually a heavy sleeper but the noise did bother me a bit and it took a while to get to sleep. Other than that, remember to bring cash. I was under the impression that the the credit card I used to secure the booking would be charged after we left but on arrival we were told to pay in cash. This was actually a major hassle for us as we were nearing the end of our trip and didn't have enough euro cash and had to go hunting around the city trying to find a good exchange rate etc. Other than that, we had a pleasant stay and I'd recommend B&B Sant'Agostino to others travelling to Rome and who were looking for nice, affordable accommodation.