The very first thing I have to say is that Nana is a very kind host. She makes sure you feel like home away from home. She took the time to explain to us everything there is to see and do in Santorini and provided a map for us to remember everything.
The appartement is absolutely perfect. It is neat, a good size (bigger than I expected) and tastefully decorated with art work from Greek artists. It is not in the heart of Fira, wich is perfect because you get to have a good feel of the local life, without being too far from the very touristic Fira (about a 10-15 minutes walk). It is located in the center of the island, wich makes it easy to either go north in Oia, or south to the beaches. You can easily commute with the public buses or rent an ATV or scooter to get around.
I highly recommand this place for your stay in Santorini. You won't regret it!