We had a great time - the location is really superb. The Trastevere district is great with loads and loads of great eating places. You are literally within 100m of maybe 10 eating places with many more just beyond that.
The flat takes a little bit of navigation to find - its worth looking at google maps (or something similar) first so you have an idea of where you are going.
The apartment itself is fine for a short city break. We had a lovely time each night sitting out on the balcony listeneing to the sounds of the city below. There was one night where there was some loud music but we enjoyed it. One of the apartments opposite was used by a jazz group for practising one evening - really good. The rest of the time it was quiet apart from the now-and-again sounds of traffic horns, some fireworks, and the occassional church bell ringing in the distance....
The apartment was clean and the air con kept everything nice and cool.
Perhaps the biggest bonus was the portable Wifi module which was in the apartment. As well as keeping you connected while in the room, you can take it around wth you giving you on-the-go access (without eating into your data allowance).
The only consideration I would have when deciding whether to rebook again would be all the stairs up. (4 levels x 2 sets x 9 steps).
It is a bit of a slog if you've been doing a lot of walking around the city (as we did!).
If your okay with stairs, this apartment should definitely be on your short-list.