Ioannis is a great and caring host. Met me at the apartment himself in the evening and gave tips on the area and was always here for any questions.
Petralona is safe in the day and night which is important for Athens. And no tourists because it's a residential one!)
There are a lot of cafes around and big supermarket nearby. Metro Petralona is 5-7 minutes away on feet, same metroline for OAKA And SEF/Karaiskaki stadiums.
But if you're coming to the city to support Olympiacos, you must know it's Panathinaikos area (as of March 2019).
City center is also easy to reach if you need it.
So I recommend Ioannis as host and his apartments! Had great time staying in the area.