This unit is everything you read in the description and in the commentary. Nathalie and Enrique are great people, they handle any problems you mention and their unit is an excellent site before you even start thinking of issues.
It is overlooking the plaza at Campo di Fiori, so there is 'noise' pretty much around the clock. However, the windows, when shut, will definitely mute the noise and you should have not problems unless you are an incredibly sensitive sleeper. You should want to stay here because of its nearness to the Campo, and the noise is a beneficial aspect of being among other active people.
The spaciousness is perfect for a couple (and as Enrique or Nathalie would say - "romantic"). Elevator is small, but fits two people, so no pianos allowed. We're heading back, what else can we say?