Marco was waiting outside the entrance to the apartment when we arrived, which was a huge help! He then took some time to show us around the apartment and provided us with some helpful tips for our stay. He was also very quick to respond to some questions we sent him during our stay.
The apartment is centrally located; no more than a 5 minute walk to the Duomo and the train station, and about 15 minutes to the area around the Uffizi. It's decorated beautifully and has everything you need for your stay.
The only thing to note would be that the walls/ceiling allow a bit of noise from the neighbors to come through, which wasn't a problem for us, but may be an issue if you're planning on going to bed early every night.