I with my boyfriend stayed in Massimo's apartment for 3 days)
The location is great, 15-20 min to Colosseum by walk)
There is a metro station 5 min by foot (Manzoni stop, orange line A), just 2 stops from Termini station.
There is also a tram stop in 2 min, which can lead you to Trastavere.
About the apartment there is no kitchen and the place where you can cook. There is hall, bedroom and bathroom.
The special thing is the balcony where you can sit and enjoy the view to the old church)
But there is no Wi-Fi (no Internet) in apartment, so for young people it would be inconvenient.
In general it is a good apartment for middle or old age people who is not care about Internet & kitchen)
Also while staying in apartment you should pay additional 3,5 euro per person per night, and 10 euro per night for the air conditioner.
Massimo met us in apartment, explained the rules of the house, gave the keys and advised us the restaurants and the shops near the house)