This is a good place centrally located, the apartment looks recently renovated, communication was easy, same with key pickup and dropoff.
Expect however to spend your stay with windows and blinds closed, like many other places in central Thessaloniki, the apartment looks straight into the balcony of the opposite building (which is a few metres away), so if you want privacy you'll have to have both closed.
I'd mention something I've seen in other reviews which is the noise from the elevator which can be annoying if you're a light sleeper, on a Friday/Saturday expect people to be using it until quite late (1-2am+). There is a electronic lock on the door that was also making a buzzing sound for some reason.
Overall it's a good spot if all you plan to do in the apartment is sleep because of the location and modern interior. I might stay here again if I couldn't find a place with a better view.