Great location in the middle of the old town in a quiet area close to the Church of Hosios David and Vlatadon Monastery. Just keep in mind that reaching the place involves walking stairs up and down and that arriving by car is only recommended for people who are confident and flexible when it comes to driving & parking in narrow and steep streets. On the other hand, that also means you can have some great views over the city from nearby viewing spots and the area is very picturesque especially at night.
The place itself was just like in the photos! The internet worked great, too, which was important to me as I had some online meetings during my stay.
Massa was very friendly and forthcoming. There was some issue with the water pressure and water heating which I didn't mind but since it can only be addressed after I left, Massa was kind enough to give me a refund anyway.
All in all, I wouldn't mind staying another night or two if I ever came back to Thessaloniki .