Not so much a Guest House as 4 bedrooms in a converted apartment on a busy noisy street, not in the quaint area of Trastevere. Worst part was not being able to get any advice or assistance from the staff because there were no staff. The owner and a helper spoke no English and were only there in the morning. Through hand gestures we were able to ask how far the walk to the Vatican was and we were told 15 minutes. It turned out to be an hour at a fast pace. There might of been a shorter way but we couldn't communicate. We got locked out one day and called the owner but she couldn't understand us. We had to call back after we looked up how to say we were locked out in Italian! She drove over and let us in after about 30 minutes. Not a place to stay if you are first timers to Rome.
This reminds me of the hotel I reviewed in Cologne. We didn't like being alone either. In fact, one night, we were the only people in the whole building. And it was very difficult to communicate with these people too. The owner showed up only once for a few minutes the three days we were there.
It might be helpful to post why you chose that place. Assume it had to do with the description or some other recommendation.