Simon's apartment is really located at the center of Roma! It is quite close to the Rome Termini, so if you travel from other cities in Italy to Rome by train, it is a best choice for you! It is also close to these major sites in Rome, basically I visited Rome by foot. The room is very clean and tide, very large comparing to hotel rooms.
Simon is a very considerate host! He greeted us with a bottle of nice wine and the map he left really helped a lot!
I would highly recommend Simon's apartment to anyone who wants a comfortable stay in Rome!