The apartment is in a good location, just 10-15 minutes walk from most key sites (including the Colloseum, Trevi Fountain, etc) and has a Metro stop just 5 mins away or the Termini station 10 mins walk. There are a number of good food stops very nearby too - you certainly won't go hungry.
Luca was a great host - kept in contact before and during our trip and even checked on us to make sure we were ok when there was a 'freak' hail/thunder storm! The airport transfer he arranged for us worked really well too.
The roof terrace is lovely...although we hardly used it as we were out sightseeing most of the time. Remember though, having a roof terrace means you have a lot of stairs to climb to reach the apartment!!