I was very pleasantly surprised with what I found. Actually, the place is much better than the photos. It was very clean and Ioulianos was very communicative. The location is perfect -very close to the heart of the city. The amenities were among the best I have seen so far in airbnb. Hot water is plenty and the A/C (which is in the living room) is strong enough to keep you isolated from the warm and humid weather outside. To give you an idea, I stayed here for 9 days, and could easily stay here for longer.
One potential issue is the relatively low shower ceiling; I am 179cm tall and I didn't have any problems but I would imagine that from 190cm (I am not being exact; I hope another visitor can clarify this in the future) on, you may have to squeeze yourself in order to fit in there.
All in all, a definite A++ from me. I would not only definitely recommend it but will come here again whenever I visit Thessaloniki.