I stayed at the apartment for approximately 10 days, and I had a great time in Athens and in Konstantinos apartment.
The flat was clean and cosy, and all essential items were present. The location of the apartment is amazing. It is situated in a lively neighbourhood and a lot of the attractions in Athens can be reached by foot from the flat.
Furthermore, Konstantino was a great host and any problems or questions I had were taken care of or answered to my satisfaction.
Should I ever need an apartment in Athens again I will consider this one as an option.