The unit is very clean and in a great location of Trastevere. I agree with some of the other commenters in that you will hear a lot of street noise as restaurants are just below the two main bedrooms. However, the windows are well-insulated and I recommend bringing a white noise machine or app to help drown out that sound.
I recommended to the hosts that they replace the bedding - both the matresses and pillows were very uncomfortable and unsupportive. Our group of five all slept poorly that first night. The next morning, I messaged Andrea and he brought us brand new pillows by noon. I am pleased with their quick response!
When we left a couple of days later, they helped us by booking a taxi van to the airport at 6:30 a.m., so I feel they are very good hosts. I only gave a 4 star review because of the bedding, but if that can be improved than I would stay here again. :)
Lastly, in Europe... what is called the 2nd floor is actually the 3rd floor, so you will have to lug your items up three flights of stairs. The young man who checked us in happily helped us with the heavy luggage, however.