Overall a good stay.
The Pros:
Great location - right in the beautiful Trastevere neighborhood but away from the crowds.
Nice books and maps in the room.
Clean room, spacious enough for one person.
Things to be aware of:
The house is slightly old you will hear loud-ish thumps everytime someone opens/closes doors or windows (I'm a light sleeper, but it may not be an issue for most people).
The bathrooms are shared as the listing mentions so you may not always find them squeaky clean (especially since the flush is a bit hard to use).
A good value for money overall.