I was happy with my stay at Chris' apartment. Chris responded to all queries very quickly and sent instructions how to enter the apartment myself with a code, it wasn't necessary to wait for someone to let us in.
The location of the apartment is good, 10 minutes walk to Aristotelous Square and all the restaurants and shops. The upper town was easily accessible as well. The view from the apartment itself and the rooftop was quite nice. Wifi speed was reasonable, 8 Mb/s down and 0.5 Mb/s up.
Having access to a washer and a dryer, with all the necessities provided was great. The apartment was very clean, no issues there. The host, Chris, visited once we settled in and even brought coffee and Spanakopita for us before we left. Very friendly chap.
The bed was quite comfortable, even for a tall guy like me: No cold metal parts that my feet had to touch, and my feet were able to comfortably go over the edge of the bed (tall people will understand).
I was not happy with the shower, however. Anyone over 170 cm tall will struggle to not bump their head against the ceiling. If this doesn't bother you, I'd definitely recommend this place to visitors to Thessaloniki.