Fantastic location. There's an escalator inside the Colosseo metro station (right hand side before the exit), which takes you up to the street level where the apartment is located. It's very convenient access to most public transport (train, tram and bus).
The apartment is very quiet and private, being in an attractive courtyard of a residential apartment building. It is clean and modern, with the essentials that you want for a short-term stay.
Antonio made it very easy for check in and check out, and communication is good. Thoroughly recommended.