The apartment is excellently located in the Campo di Fiore area. It's only a few steps to a pedestrian bridge that takes you to Trastevere where you can find a lot of good restaurants.
The apartment itself is relatively small, with the bedroom in a loft area above the bathroom. The kitchen is just a sink, mini-fridge, and double hot-plate. Only basic utensils were available. The bathroom is small and cramped, but similar to most we found in Italy. As noted it is a below ground unit with no natural light. While we didn't find this to be an issue, it can be a little disorienting. The other issue this causes is a lack of cell reception in the unit. This is overcome by the wifi, however halfway through our stay the internet cut off completely. I believe the data limit for the month was reached, and we were out of luck. This made the unit even more cut off from the outside world and was a major issue for us.
We found the bed and pillows to be very uncomfortable. I asked for a second pillow, which I received, however I still woke up most mornings with a sore back or neck. Compounding the issues, was construction in the neighbouring unit that started at 8am. The workers sounded like they were hammering and chipping tiles off of a wall or floor. This was only a few feet away from my head as I lay in bed. Not exactly what I wanted from my vacation.