Alexandra is a very responsive host that will support you on various matters, but there are some issues where her hands are tied. And these are exactly the issues you should be aware of to plan you stay in Thessaloniki thoroughly.
The 'KeepItClassy' apartment can become a stay of choice to any party-goer or nightclubber. It has a nice location, a couple of steps from the waterfront, surrounded by numerous places to spend the night eating, drinking and/or dancing. But if you prefer to have a rest at night then consider something else.
A few reasons for that are mostly about the poor soundproof:
1) There's a night club or something in the building, so starting 23 p.m. the super heavy bass will keep you awake until the early morning (maybe, it's only in the weekend, I don't know, we spent Fri-Mon there)
2) The apartment itself is not that big and mostly occupied by a king-size bed. Which means a fridge stands next to it, and, as any other fridge, it buzzes. You might get used to it, who knows. We didn't.
3) If you open up the window for some fresh air, be also prepared for the noise of a cooker hood from the nearby restaurant. Kitchen smells are included.
4) You will hear literally everything from the corridor: elevator, other people's steps, cough, lough etc.
5) Not a soundproof issue, but of importance to those taking care of IT safety: the wi-fi there is shared with four other rooms so people will have the same password as you do. Better keep it in mind.