The apartment is centrally located between the train station and the Duomo, so you don't have to walk too far with your bags and then you aren't too far from the major sites in Florence.
The steps were steep, but worth it for the great space- large and very airy- and Francesco was kind enough to help me with my bags! If you are in decent shape, it shouldn't be an issue for you.
While the area was quiet, I also felt safe as a female solo traveler walking to and from the apartment, even at night. Francesco was a great host and I'd happily stay here again when I return to Florence!