Great place to stay, comfortable and as advertised. Listed as appropriate for three people to stay in comfort, as indeed it is. Another comment says it could comfortably sleep four, which I disagree with, but Diego isn't the one claiming this.
The place is comfortable, well-appointed and clean. Diego is a pleasure to deal with, making the whole process very low-stress.
My one tiny criticism is that the place is not as bright as it looks in the photos - it is below ground level and getting as much natural light into the place as the photos suggest could not be done without great effort. This is not to suggest that the place is completely dark - the levels of light are fine.
The location was quite good too - right by a Metro station and within walking range of plenty of landmarks and good restaurants.
Overall I was delighted with the place and would recommend it to anyone who stays in Rome.