I stayed at Serenas apartment for 3 nights and loved it. It felt like home....the room I had was very spacious, the bed was comfortable and the bathroom very clean and nice. Serena was very helpful on my arrival and pointed out on a map some nice restaurants to try, a local supermarket and internet cafe around the corner. The apartment is very secure which was very important to me seeing I was on my own. The Vatican City is just on the next corner and it's very easy to get to all the other tourist landmarks via the Metro train.
The only negative I would have is that there is no air conditioning in the bedroom...but I left the window open at night and the breeze was quite nice. Also the television reception was not great.
But all in all my time there was fantastic and I would definitely stay there again.