Liv'In Roma is a great central location for exploring Rome! Every major site is about a 20 min walk away, which is totally doable! Bring good shoes :) We took the train and then bus into the city and used her car service going home. Use the car service! The apartment isn't very convenient to the metro and switching trains and buses isn't what you want to do after a long transatlantic flight.
Overall great place and I would stay again!