Staying at John's place was great! The apartment is well-connected to the bus system, although a little bit outside of the city center. Kalamaria itself though also has nice restaurants and cafes.
The apartment was clean and exactly like the photos. John's communication throughout the arrival process and while we were in the apartment was great and could not have been better. Like other reviews mention, the bed is very comfortable! As we stayed for ten days, we even used the kitchen to cook a few meals, which was no problem at all.
One small note - the ceiling in the bathroom is lower than in the rest of the apartment. My boyfriend is 1,90 m and his head touched the ceiling while in the slightly raised shower. It wasn't a big deal, just something to bear in mind.