I can't recommend Paolo's place more highly: the terrace is spectacular - there is nothing to compare! But the rest of the place is super comfortable, clean, quiet, and a great central location to explore Rome. Just off the edge of the Termini touristy area, so you can access that if need be, but next to a GREAT wine store, gelateria, some basic Roman trattorie, etc. Plus easy walking to the two major museums of Roman antiquity - especially the much underrated Palazzo Massimo.
If it is available, you should book it! (Tho it is on several levels, so be prepared).