We went at Panos' place for 4 days, everything was perfect.
Located near the center, everything is within walking distance (max walking distance you may have to walk is 25min to the white tower, which is located at the opposite of the town) we never took the bus. If you don't want to walk there are plenty of bus stops around that will take you where you want to be. The bus from the airport is about 5-10min walk (considering luggage). There is an elevator in the building so you won't have to take stairs with your luggage. If you want to buy groceries the supermarket is right in front of the building and provides you with a large variety of goods at a cheap price.
The appartement was very clean and provided with all the commodities (soaps, washing machin, towels, toilet paper, salt and pepper, oil, etc.) The appartement is fully decorated with good taste and quality furniture. The fact that the AC isn't in the bedroom makes it possible to enjoy a good, fresh night without the usual noise of an AC.
There are 2 balcony, one that goes on the street and a smaller one that goes on a quiet space. 2 living room: the first one with a TV, 2 sofa and a desk (with a small sound system with a good sound if you want to play music instead of watching TV). The other one have also a sofa and a small desk. The bedroom is very comfy and the bed and sheets are of quality. All the windows are doubled which makes the appartement quiet all day long. The kitchen is fully equiped and provides everything you may need to cook and store both frozen and fresh goods.
We never met Panos but we had the pleasure to be welcomed by his sister Eleni, and their lovely parents that made us a wonderful treat . Eleni took care of our arrival and explained to us everything we needed to know to enjoy our stay. She was very kind with us and always available by message for every question we may have. She answered very quickly and gave us clear informations.
Overall we highly recommend this place to stay in Thessaloniki as we had a wonderful time. Provided by everything you may need and orchestrated by lovely, warm and welcoming people.
Thanks again to Panos' family, you're the best, don't change anything :)