To make it simple I will just say that believe what every other positive review says is true, if not more so. Chiara and Lucia were very communicative and easy to deal with before our trip and upon our arrival. And yes, a delicious tart was waiting for us!
The apartment is an exceptional space. A nice size, with a very comfortable bed, and a perfect location. You are both in the heart of Trastavere but on a quiet street that allows you to get away from it all. I would say the apartment is more attractive in person than the photos would even suggest.
One minor note: the shower is a bit small, as is common if you're used to older urban buildings. My partner and I found it just fine, with plenty of hot water, but just a heads up for those who might be particular about such things.
But you would be a fool to pass this apartment up. Everything was marvelous.