We stayed at Carmine's for a 4 night trip to Rome and I cannot imagine a better place to have stayed.
Comfortable beds, a powerful shower, basic kitchen (which was more than enough for making coffee!), and amazing location. With delicious pastries for breakfast from the bakery opposite the front door and delicious pizzerias and trattorias a short stroll down the road for tea. Don't miss the gelataria on the nearest piazza, I am slightly sad I did not try this earlier in our trip as it is amazing!
Rome is a compact city, and from Carmine's place we visited all the main sites, and some I did not know before I came by walking (Vatican, Colloseum, Panthenon, Spanish steps, Trevi fountain, Villa Borghesi...)
A wonderful stay. If we return to Rome I would chose here to stay again.