We (two adults and our three kids: 14, 16, 26) stayed in the Golden Keys' for four nights and enjoyed every bit of it. The place is newly built and has well appointed utilities. The Golden Keys is a large apartment with three separate bed rooms with individual baths each. The three bedrooms share a small kitchen which is also used as central room. The whole layout feels more like an upscale hotel, and the rooms are very private.
The location is adjacent to the Rome central train station. The neighborhood is typical for such a location: mixed residential, not quite upscale, but definitely safe. There are a few restaurants right around the corner which invite sitting outside in the evening.
The Golden Keys is located a bit outside the central part of Rome. The metro line does not go into the center of Rome, but it does go to the Vatican which is therefore easily accessible. The Colosseum and Forum Romanum can also be reached by foot. If you stay less than a week the location will definitely be ok, but if you stay for two weeks or longer, you may want to optimize to reduce walking effort into the city.
The Golden Keys can be easily reached by train from the airport by a direct and fast connection (30 minutes). This is the fastest possible way to get from the airport to the Golden Keys. Since we arrived late at night (and we weren't yet familiar with the neighborhood) our hosts have organized a van pickup from the airport. With five people in our group the cost is the same.
Our interaction with our hosts was very pleasant. Responses were without delay, and we received a detailed introduction to the apartment.
In conclusion, I can highly recommend the Golden Keys, especially for larger parties.