Amazing location, comfortable apartment, five stars.
The apartment is two minutes from Piazza Navona - easy to walk almost anywhere in Rome. Lots of good restaurants in the neighborhood, too. The apartment has a nice kitchen and we were able to cook several nights.
It's a spacious, loft-style apartment. Note that the bed is on the top level and the bathroom is on the lower level, so a midnight bathroom trip requires a flight down a tight spiral staircase.
It's Rome, so there is a fair amount of street noise, and the shower is on the small side. That said, those are minor quibbles. It's a comfortable apartment in a convenient location, and it's a great value. I would definitely stay here again without hesitation.
Last note: if you stay here, make sure you stop by Santa Maria della Pace (literally around the corner) and see Raphael's Sibyls. Enjoy!