Maria's place is absolutely lovely. My boyfriend and I really enjoyed it!
The location is *fantastic* - it's right next to Piazza Campo de Fiori which is great by itself, and is also a great point to head out to other locations in Rome. It can get a bit noisy at night (because it's very close to pubs\restaurants), but if you close the windows it's not a problem.
The place itself is very comfy and beautiful - makes you want to stay there more even though there is so much to explore in the vicinity of the apartment.
Maria was very responsive. We had an accident in the kitchen which caused an electricity shortage and she responded very fast and sent someone to assist us right a way.
In short - highly recommended if you're going to Rome!