We had a very very good time at Martinas Appartement. It is easily big enough to host 4 people for a long weekend of sightseeing in Rome.
The appartement was very clean and the 2 bathrooms are super handy. The living room is big enough to have a good breakfast and the kitchen supplies everything you will need (Dishes, Coffee Maker, basic spices, etc.).
The street in front of the appartment (you are in the 3rd floor) is quite noisy in the night, but when the windows are closed it is alright.
There is a 24h supermarket and metro station just 5 mins away and at the front entrance there are Cafes, Restaurants, bakery's etc.
The Appartement is located just north of the vatican, so the city center is not far away!
All in all, definitely recommended! :-)