We stayed in apartments for a several weeks and that was great experience for us. Panos family is very friendly and hostile, we had everything we need.
Apartment is well furnished, clean and shiny, with autonomous gas heating which makes it as warm as you want, which is important if you travel with kids as we were.
Internet connection is very stable, during our stay I was working from home and didn't get any issues.
If you travel by a car it won't be a problem to find place near the building, especially comparing to other locations in the center of Thessaloníki.
Also, what we very liked - is supermarket right across the street, I believe it will save a lot of time for every traveler.
Location is good as well: 7-10 minutes of walking to Ladadika(district with cafes and nights clubs), 15 to embankment where you can feed seagulls, 10 minutes to the central market.
I suggest to visit Kalachori lagoon to see flamingos, take something to zoom them as they can be too far to see, but we were lucky to watch at one in a close distance. Technology museum is worth to visit too.
And if you want to know more about history of the city - go to White Tower museum, they have audio guides and a lot of information. I guess you will need 1-2 hours to listen to everything. Come in advance as in winter they closes at 3 pm.