Petroula&Giannis’s place is exactly like shown in the pictures, if not a little better. Communication with Petroula from the very beginning was quick, and courteous. I was set to arrive a little earlier, and they were willing to store my bag while the apartment was prepped. Luckily, I arrived closer to check-in time, and Panos (their friend) was there to greet me. He was very friendly, did a walkthrough of the place, and gave me great tips of the area.
Taking the metro from the airport to the apartment is very easy. They have signs in English as well, which makes it a breeze.
To walk to the Acropolis, you have to cross the Filopappou Hill Park, which is pretty big. I got lost for a second because some of the trails were not very well marked, so my suggestion is to not do it late at night (I think the park closes at some point, too). Luckily I had Google Maps to guide me.
The apartment has great amenities, including a washer, which is something I look for because I like to pack light. They also left a nice Greek wine for me (nice touch), and they had toast, jam, and coffee. Totally recommended!