This nice apartment is located 100 m from Santa Maria Maggiore square, we thought it was very central: close to Termini central railway station, 13 min walk from Colosseum and approx. 20 min walk from Fontana di Trevi, thus the most important sites are within walkable distances.
Our "verde" room was on the 4th floor, but the building has a small elevator so no worries about taking the heavy luggage upstairs and the windows were facing the inner garden so the stay was very quiet and excellent for relaxation. The apartment was as described, room has air conditioning and it's own bathroom with shower and bidet. Common but VERY WELL equipped kitchen.
There was no trouble with picking up the keys, even though the owners were on vacation. The city tax is not included in the price so count on an extra payment (cca 28 EUR for 2 ppl for 4 nights). We had a nice welcome, co-owner showed us around in the apartment.
The maid came every morning to clean up and make the beds, which we were satisfied with, but you can also say no to this little extra although it's included in the price.
There was a minor problem with the weird electrical toilet (seemed like it was clogged before our arrival), which the staff has noticed and fixed as soon as possible.
We received breakfast vouchers for every morning (8-11 AM) in Bar Cottini at Piazza di Santa Maria Maggiore for a coffee + pastry of choice - which was an excellent way to start our day.

Summing up, the place is great and I recommend it to anyone who is traveling on a budget. Excellent location. Will come back again.