Stayed here with the boys for 3 nights in October. We had a great stay. The location is outstanding, when sitting outside you can see the Colloseum, there are grocery stores at a few minutes walking distance, as well as a metro station and plenty of places for a bite and a drink.
Valerio offers great service. For example, I texted him about a frying pan (we couldn't find one). The next day there were two brand new ones, along with a new perculator, in the kitchen!
The apartment itself is spacious enough for four people, with two beds and a bathroom. The apartment is clean and the shower is nice. The only downside is the amount of kitchen materials and toilet paper. Like the frying pans, glasses and other tableware were also scarce. But hey, with a service like that, it wasn't even a problem.