I stayed at Olga's place for a week. Everything was exactly as described. Her apartment was very clean and the bed was comfortable. Privacy was respected not only by Olga herself but also by the fact that you have a private toilet (bathroom is shared however) and a private balcony with a table. The neighborhood is generally quiet at night. In general I'd say it's good for a short stay.
On the other hand there are some minuses (in case you haven't noticed from the description):
- Walking from Olga's place to the center takes half an hour. The White Tower is even further, about an hour. You can take the bus but it's not too reliable, not to mention there was an ongoing bus strike during my stay. The scorching heat in July surely didn't help. (Thessaloniki doesn't have metro.)
- There was a desk in the room but it was rather small and had no lamp.
- It seemed that there was only one power outlet in the room (at least I didn't find another), so it wasn't possible to charge the phone and use the fan at the same time. Speaking of the fan, there was no air conditioner in the room. However I was okay with it because it was normally windy during the day and cool at night.