Couldn't get a hold of the apartment owners/staff before arrival to arrange check-in (as instructed to do in the reservation), but was relieved to find the staff waiting for me at the front door upon arrival. Don't stress if you can't reach them before arrival.
Up a couple of flights of stairs in an old building, so be prepared, no lift. We stayed in a recently refurbished junior sweet. Very clean, modern and comfortable. Very friendly service (when around), great wifi, nice breakfast across the street (great dinner there as well). Nice location, 5 minutes from metro station, heaps of shopping,restaurants and historical sites nearby.
Highly recommended, as long as you can climb ~40 stairs. Would return next time in Rome!