Everything was perfect - except the mattress in one of the bedrooms (more below).
The apartment is ideally located, just the right size, well equipped and quiet (which would not be the case on the bigger road just round the corner or in many other small streets nearby that are lined up with crowded bars and restaurants). So not just the perfect neighbourhood (so close to everything) but also the perfect street (quiet).
Another very positive comment: Toni lets his guests use his office from 10 a.m.-5 p.m. to drop off their luggage. Our last day in Athens would not have been the same if we had had to carry our bags. Also, communication with Toni is very easy.
However, there was one big problem in the back room: the mattress. There is a hole, not an actual hole as the fabric is not torn, but a cavity. My daughter, who's 12, slept on that side of the bed and said it was sort of ok but my son, 16, would not have been ok with it and I would not have been able to sleep. A child can sleep head to toe, but no adult would be able to sleep on the mattress. I can only guess that some kids jumped on the bed and a couple of strings broke. The person who cleaned the apartment and prepared the beds could not not have seen it. The hole or cavity is just so visible, it's not just that you feel it when lying on the bed... you see it if you lift the duvet. Seriously, I am not exaggerating. No-one would be ok with the condition of the mattress. I did not inform Toni while there as my daughter didn't want to ruin the holiday and didn't mention it after the first or second night- but I saw it the morning of our third day and was very unhappy. I knew there was too little time to have it replaced before we left the next day so I didn't bother, enjoyed our time in Athens and informed Toni after our departure.
So before booking the apartment, I would ask if the mattress has been replaced.
Again, everything else was absolutely perfect.