My boyfriend and I spent an all too brief stay (just two nights unfortunately) at Mattia's place. We love love loved it!
The house is in a great location; close to lots of sites, restaurants, cafes, shops, etc. The place is clean, nicely decorated (very Italian), and large for a city place.
It was super fun to spend our evenings relaxing in the jacuzzi and steam room. You really cannot beat the price for your own private mini spa!
Mattia was super friendly, very responsive, and flexible with our check-in and check-out. We were even provided with a small map of the city and a homemade guide to the neighborhood. We tried a recommended cafe and two restaurants (the vegetarian place just a few blocks away was awesome--even my meat-loving boyfriend agreed).
Rome is a regular stop for us and we definitely plan to stay here again!!