I highly recommend Maria's apartment. It is very well located, in a central but quiet neighbourhood. It is decorated with taste and the private cute little courtyard has the most beautiful painted walls.
Nothing is missing either in the bathroom (from shampoo to insect repellent, hair dryer), the kitchen (fruits, eggs and marmelades in the fridge, spices, expresso machine...) or the office (wifi, printer, laptop). The iron and ironing board were much appreciated.
You feel like being at a friend's house. Maria and Dimitris are perfect hosts. They welcomed us warmly and indicated us a good place to eat in the neighbourhood (which eventually became our favourite lunch place). They have a nice list of places where to eat and drink at Heraklion, so that you are sure to always make the best choice. They didn't hesitate to come and help me when I had difficulties with the printer. And, as there wasn't any other guest the day that I left I was able to leave in the middle of the afternoon. I really enjoyed my stay and it is the only place to stay in Heraklion.