Marcella's apartment is very comfortable and well located. If you want to be close to everything, it's an excellent choice!
During our stay we walked to all the main attractions, but you could just as well get a bus nearby at Chiesa Nuova. Getting there from the Roma Termini train station was an easy bus ride and a short walk away.
Piazza del Fico has a buzzing nightlife vibe, with good music and late night drinks available within a few steps of the apartment. We enjoyed our stay very much because of that, even listening to some of the great music coming from the bars downstairs.
Even though the piazza is busy, the double-pane windows shut down the noise quite well. Marcella left earplugs for us, in case we needed them, but II never felt the need to use them. You might want them if you are a light sleeper, though.
One important thing to note is that the apartment is on the second floor, with no elevator. So if you have heavy luggage, you will have a hard time going up! In our case, it wasn't too bad, as we only had to do that heavy lifting coming in and leaving.
If you don't mind a little noise from Rome's nightlife and carrying your luggage up the stairs, I can't think of a better place to stay. Great value! Would definitely stay there again.