The apartment is a total delight - clean, cozy, very quiet with everything we needed. The terrace is so so nice - a wonderful spot with pretty flowers and plants to spend time and listen to the church bells ring.
As others have mentioned, the apartment is up several steep flights of steps so wouldn't be for those who have a hard time navigating stairs but this was not an issue for our family. The bedrooms were so cute - and despite the extremely lively neighborhood of Trastevere, which was active and full of people into the wee hours, once we were upstairs we heard not a peep from the street. The air conditioning was great and very needed as it was in the 90s every day we were in Rome - note that there is no AC in the smaller bedroom but several fans were available and we were all comfortable. The two bathrooms were very convenient, everything in the kitchen worked well. The terrace as I mentioned was wonderful - it's across a little hallway outside the apartment.
Last, the location of the apartment was perfect we thought - right in the heart of of a fun neighborhood with tons of restaurants and a block from the Ponte Sisto which we walked over daily to get to different parts of the city and r. We had a great time!