Traffic on the Prenestina is maddening. Reception staff is slow and not welcoming. Rooms are gorgeous, as is the food. No amenities (spa, gym, swimming pool, etc.) to speak of. Lines at front desk are ridiculous. Policies are stupid: must pick up Internet logins at front desk, can only get 6 hours at a time, key cards stop working on checkout day after 10a.
The hotel seems to have been built with conferences in mind, but seems to cater mostly to mass tourists by now. If you like spending time in your hotel room, this is the place. If you like exploring around, the traffic will sour you to this place. If you don't like waiting in line, go somewhere else.