What a great find! Toni's apartment is spacious and furnished with all the essentials for a break away. The location is great for walking to the city centre and is very close to the stadium, and is also easy to reach on public transport (from the airport, take the metro line 3 to Syntagma and then take tram line 6 one stop to Zappio).
A few reviews mention the noise. It's true that the apartment overlooks a main road and it does get busy at times, with the occasional siren as well, but this never reached more than background level during our stay (February) and certainly didn't stop us from sleeping. If you're expecting total tranquility, though, there may be quieter locations (at least overnight) away from the busy roads. For most visitors, it should not be a problem.
Check-in and check-out instructions were clear and Toni was polite and responsive. We were very happy with our stay and would highly recommend :)