A very nice place.
I will echo what other reviews have said - very comfortable bed, clean, pretty space. It is true it's on the top floor with no elevator but I'd say it's only like 3 full flights of stairs and really not too much for a reasonably fit person. Note though that the stairs are very old and are uneven - if you have any balance/mobility issues I would say this is going to be too much because they are kind of slanted and lumpy.
Ludovica had it stocked with espresso capsules, milk, juice, water, etc. Basically everything you need! She was gracious and helpful and I could tell she wanted our stay to be perfect.
My favorite thing other than the comfortable bed was the lovely view from the couch. It was a great spot to sit and read while looking out over the rooftops. It was so relaxing!
A few notes, which are NOT criticisms but just helpful info for your planning
1. Even staying there in December - the off season - we were woken every single night by loud drunks in the street below at around 2-3 AM. Not the host's fault at all, it's just the neighborhood. I would have expected this more in the summer but was surprised it's even an issue in winter when there are less tourists. If you don't know Rome, Trastevere is a great area, very picturesque and lively and near all the major sites, but it also tends to attract a party crowd that is active well into the night.
2. If you want to use the fireplace - it does work but it's very, very smokey and I don't really recommend it. The chimney probably needs cleaning.
3. There is no oven of any kind, just a stove.