Lara and Christian were great hosts, and while their flat isn't in the centre of Rome, it's near a metro stop and so you can get into the centre in about 10-15 minutes. There are also some nice restaurants and bars nearby, and other amenities such as a 24 hour supermarket. The apartment is also a short bus ride from the Catacombs of Saint Sebastain, which is well worth a visit.
We were given lots of advice of things to see and do in Rome, and any queries I had while over there we're responded to quickly. Just don't forget about the cleaning fee which has to be paid on arrival- I'd book our stay months in advance and so had forgot about it! Overall, a brilliant place to stay, and one I'd recommend if you are happy to have a short commute to the centre of Rome.