The hotel's location is extremely convenient, at two minutes (one minute if you get lucky with the traffic lights) of Roma Termini, but nevertheless once you enter the gate, you feel like being in a remote luxurious place.
The hotel itself is certainly worth its 5 stars - excellent service, very friendly staff (at the door, at the reception, in the restaurant and the cleaning people) and spacious (and quiet - the windows' glass must be extremely thick since I didn't hear any sound coming in from outside) rooms.
I'd certainly consider returning, the next time I'm in Rome.