We had a good time staying at Marco's. The room has a private bath, as advertised. There are two other rooms which share the common kitchen area - the common area has a camera. The bathroom is pretty small, but the layout of it required all of us to sit sideways to use it, which wasn't a huge concern but something to note. There also were used items in the mini-fridge in the room when we checked it.
The place is within a building of apartments, a 10 minute walk from Roma termini (train station) and a 15 minute walk from the colosseum. It is close to the train, but far from other siteseeing activities, but a bus/metro pass allowed us to get places easily. The wifi worked well as did the AC unit.