Georgios was the perfect host. Even though due to various reasons (such as the coach breaking down 20km from Thessaloniki) arrived several hours later than I had told Georgios, instead of being upset with me, he was super nice, friendly, and welcoming.
Next, there was the pleasant surprise of finding the fridge was stocked with various drinks.
As for the apartment, although it is compact, as you can see from the photos, the available space has been used extremely well. The design is modern and practical. The kitchen has everything you need. The sofa bed is very comfortable to sleep on (even for several days). The Wi-Fi is very fast. The air conditioning will keep you cool even in the hottest days. The spacious terrace with its table and 2 chairs is great for breakfast/dinner or for working out.
As for the location, it is extremely hard to beat since it is right across the road from a large supermarket, 10 minutes' walk to the extremely popular Ladidka quarter (with its many excellent cafes, restaurants, and bars), 10 minutes' walk to the train station, and very close to several bus stops that can take you to almost anywhere in the city.
Will definitely be coming back to stay here next time I visit Thessaloniki.