I stayed one month at Giannis's apartment. It can't be better situated, in the heart of the old town. All the city's sights are within walking distance. There is enough quality amenities in the apartment for a stay as long as I did. A very good WIFI connection too.
But the very best part is the kindness of Giannis and his help in all situations. I had several little problems which he helped me to solve.
Definitely a place to stay in Heraklion!