I'd like to begin by mentioning that this is not a hotel, but more like a bed and breakfast. Also, it was not that easy to find - it is actually on the 4th floor of a residential/commercial building. The tip is to look for the Chinese restaurant that is right next door called "Lon Fon". Once you are in front of the giant front doors of the building, press the button for I Giardini del Quirinale and the staff will let you in. Walk to the end of the lobby and take the lift on the right hand side of the building - you will need to walk up an extra flight of stairs after that. Breakfast is basic and is actually located in a separate apartment a couple of floors below.
Pros: Convenient location (if you take the train into Termini from the airport, recommend walking to the hotel, don't change on to the subway which requires just as much walking!), free internet, free breakfast, friendly staff, modern and well-sized room, the BEST mattress we have ever slept in (better than our own), pleasant "welcome surprise" in the room.
Cons: They ran out of hot water half way through my shower one night and it didn't come back until the next morning, strange entry/exit policy (you must leave your room key in the hotel common area every time you go out; they have security cameras in there but it is not manned at all - needless to say we did not feel comfortable about it because any of the other guests could have picked up the keys and accessed our room. Also, there is no code/key for the giant front doors of the building so you have to buzz them every time - even if it is in the middle of the night!).
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC