I stayed at Sokol's apt for a 5 nights stay (thu-tue). I was travelling alone. It was not my 1st time in Athens.
Location is central and easy to reach. Rough around the edges but THIS is Athens, no different than most part of town. Safe it is.
Place is stylish and bed is confortable.
Some things to consider: The whole building is turned / being turned into Airbnb rentals. at the time of my stay, there were fully renovating 2 apartments right below: Noise from 9h00 until 21h00.
The hot water is controled in another rental unit. So you can run off of hot water. The front office was quick to solve the problem. But I recommend they modify the system so you don't depend on another renter forgetting to leave the water heater on.
With these 2 things in mind, it is still a good value and confortable place to stay in Athens.