My girlfriend and me stayed for 3 nights. Sebastian welcomed us very well, he is very nice and kind, and gave us some nice tips about the neighborhood.
The apartment itself very cozy, great for a couple who spend most of the time traveling outside. It's clean in a nice building with an old fashioned elevator :) The apartment is even better than described and even a little bit bigger than we though.
The location is dreamy in cool Trastevere, It's THE place to finish the day with a beer after traveling around all day. Right under the apartment there's a nice cool fresh market in which you can find vegetables, fruits and (of course) pasta (it's closed on Sunday). 3 Minutes walk from the apartment you can find anything else: Pizza, pasta, gelato (and what a gelato!), piazzas, supermarkets and anything else you'll need. Public Transportation: we used it only to get to and from Fiumicino. To all the touristic places you can go by foot and to enjoy wonderful Rome.