Although Jack wasn't available to receive us, communication was great. Fabio, the person who received us, is a very nice person that even helped us to carry our bag all the way up to the 4th floor. Kudos Fabio!
Apartment is in great location, very centric, we almost covered all the places we wanted to visit on the first day (Trevi fountain, Pantheon, Piazza Navona, Castel Sant Angelo, Vatican City). It has all the basic amenities you need, but the cell phone signal wasn't too good for me, so I struggled a bit accessing the internet.
Getting to the apartment from the train station is easy, but if you have bags and it's high season, then you may struggle on the sidewalks (compared to other cities I've been) as there are usually lots of tour guides around the area.
Getting to the 4th floor may be hard on you if you usually struggle with stairs.
I would definitely recommend this place if you want a centric location and don't care about using the stairs and wifi.