We stayed at Daniela's place for 4 nights in December, and although the place is amazingly located and was more than big enough for a couple like us, there were a few details which made our stay less enjoyable:
1. The heating was not working. We communicated with the host regarding this and she eventually, on our last night, provided us with a space heater but it also wasn't enough to heat up the room to a comfortable temperature.
2. It was very humid inside. Ventilation inside the room is quite poor and the room has no windows, and thus a lot of humidity accumulated on our clothes during the day.
3. There's not enough hot water to take a shower long enough to wash one's hair, much less for two people to shower comfortably. My partner and I have both long hair, and as such we had to take turns to shower - one of us in the morning and one at night - and even then we had to shower very quickly.
4. The Internet connection is very poor (I was getting maximum data rates of a few kilobits per second) and there is absolutely zero cell phone signal reception inside.
5. Although the apartment was 90% clean, we did encounter four (4) spiders on the bathroom ceiling during our stay.
That said, the studio is very centrally located and we were able to walk everywhere in Rome from it. The bed was very comfortable and the provided linen's and towels were very clean and well kept. The kitchen is small but functional, and we were able to use it without any issues. The decoration and lighting were cozy.
All in all, this place is probably best for short stays in warmer months and if you're not planning on spending much time there during the day, only returning to sleep.