Pina's title is not lying. This truly is the best apartment near the colosseum. We (my wife Tina, our 7 months old daughter Elise and I) stayed there for 4 nights during the Christmas season. Upfront, Pina provided us with clear information on what was available and not. Especially when travelling with a baby, it's important to limit the luggage. Since the apartment is very well equipped, we were able to do so. We were even welcomed with a nice bottle of wine and Pina had taken care of a baby chair especially for us!
The location of the apartment is perfect. You can visit the city on foot, or take tram, bus or metro which all stop at 300m from the place. It's rather silent in the area, apart from normal city sounds. Shops and restaurants are available in the close environment. The documentation in the apartment provides some background on where to eat and shop.
Comes highly recommended!