My first thought was that the apartment was much bigger than I expected! It's sort of a long and straight layout starting with the bathroom on the far end, then the kitchen, living room number one, bedroom, and living room number 2/second bedroom on the end that looks out onto the street. That room can be a little loud at night as Trastevere is certainly a late night out district, but the noise is easily erasable by closing the shutters and turning on the fan. The apartment is well stocked with everything you could possibly need, the wifi is great, and the bed is comfortable.
As far as the geographical location goes - if you like night life, this is a great area to stay in. But, as our cab driver told us when he dropped us off, it's 90% tourists and 10% locals, and we generally prefer quieter, more local type neighborhoods. However, all the food in the area is great! It is a bit of a walk to get to the historic center (Colosseum/Roman Forum/Spanish steps/etc.), and there's not really easy access to public transportation in Trastevere (except taxis), but Trastevere in itself is fun to explore and we typically prefer walking anyway. If you only have a few days though and you want to prioritize more typical Roman site seeing, you might want to stay further into the city center or somewhere on the metro line.
Also, our host was very accommodating and responsive, and I would certainly recommend staying with her! We had some trouble with the hot water, and she was quick to respond and made daily efforts to try and get the issue resolved. While it wasn't actually fixed during our stay, we feel like she made every reasonable effort to do so (it sounds like the whole water heater and possible some pipes might need to be replaced, which is not doable in just a couple days with guests staying in the apartment), and she gave us a partial refund for the trouble.
Overall, if you are interested in checking out Trastevere and you enjoy night life and great restaurants, I'd definitely recommend this apartment!