Konstantinos's place is located at a very strategic location, super close to main shopping street with tons of good food and cafe options, walkable to metro station, parliament, plaka, and acropolis. The place can be hard to find as it is in small building but if you follow the map, it should be okay.
The place looks like the photo, clean, cozy, with all necessary amenities.
We stayed there for 3 nights and the place was simple and cozy. Few points you might want to take note are 1.) the elevator in the building in not of standard system and rather small so if you are big size, might can only fit one-two person max per trip 2.)Wifi is not very fast, we were not able to upload photos to blogs right away 3.) Konstantinos was great host, he was very on-time for all meetings and greeted and welcome us in person but his responses via airbnb could be a bit slow (like 1-2 days late ) and he does not prefer phone-based messengers so make sure you have all communication settled, last minute chat might not work.