I spent a week at Elena's place, it's a great rooftop apartment on top of a 19th century building. You basically have the roof terrasse to yourself. The apartment is charming, the wooden structure of the roof gives it a cozy atmosphere.
It has everything you need; equipped kitchen, airconditioning, wifi, washing machine. And the location is great. Very central, 10 mins walking distance from Roma Termini station, and bus / metro stops are also nearby. You can get around easily from here. And even though it's right in the center, it's on a quiet strip. At night there's no noise or traffic.
If i had to name a downside, it would be the lack of height in the bathroom. The other rooms are fine, but for some reason the floor of the bathroom is elevated, and due to the slanted roof, space gets cramped. I'm 1m83 / 6 feet and bumped my head several times on the wooden beams :)
But the pro's easily outweighed that single con. Would stay again.