The location is fabulous and the view is every bit as good as described. And because the building has an elevator, being on the fifth floor (or fourth, for non-Americans) is no bother! This part of Trastevere has more locals than tourists, with so many great shops and restaurants right near by.
The only downside I can think of is that the water in the shower never goes above lukewarm, and we could only get cold water in the kitchenette sink. There were no linens available for the fold-out beds, but it is possible they would be provided if specifically requested - we did not ask.
All in all, a wonderful experience!