Just spent a week in Konstantinos' place - it's a bit on the basic side with the atmosphere of a (rather nice) student's flat, but it was very clean, has everything that's needed and if you aren't expecting a luxury hotel, it's totally fine for a while.
It's in the middle of the city, so there's a bit of traffic and noise, but on the other hand, you can walk to all the touristy places, and you're in the middle of Koukaki, which is a great neighbourhood to be in - far enough from the tourist hot spots, but still lively, cozy and authentic.
Communication with Konstantinos was fantastic and very quick, which helped me a lot because I needed a place on short notice, and he was very helpful with that and any other questions. Definitely recommended, and thank you very much :-)