My family and I spent five nights at Toni's place as the first part of our Grecian adventure and had an excellent stay with easy, simple logistics. On the whole I would say it was 90% great with just a few things I would change.
First off, the good: Communication and check in were a breeze. Toni was able to answer any questions we had in advance of our trip and for check in had a friend of his meet us nearby to let us in to the apartment and give us all the details we would need for our stay, which was especially nice since we arrived on a national holiday.
The apartment is appointed in a modern style, sparse but stylish and looks very nice and clean. Beds are firm but comfortable and everyone slept very well, especially since all of the bedroom windows basically have black out curtains.
For the medium: the location is okay. Very close to metro which is nice but the neighborhood leaves some to be desired and we were very relieved to see how nice the apartment was after walking through the neighborhood. A lot of trash and a lot graffiti (though this seems common in lots of places in Athens). Oh, and we did also see some roaches in the apartment's bathroom. :(
Overall, Toni's place worked well as our home base.