We really enjoyed staying at Paolos place. The apartment is close to everything you need and it's super easy to explore Rome from there. Not to forget mentioning the nice Gelato downstairs :)
The only concern some people might have is that you hear your neighbors sometimes through the a little bit thinner walls, but that wasn't really a problem for us at all.
The breakfast is good and includes tea, coffee, cake & toast and they kept everything looked after although we only met someone once for the check-in.
All in all we can really recommend staying at B&B Liberta 4 while you're in lovely Rome!