This apartment is in a fantastic location. It is right on a pedestrian-only street, and is a 2-min walk away from the Syntagma Square metro station as well as walking distance to the Acropolis, dining, and of course shopping.
Being in such a central location, I was surprised at how quiet it was inside the apartment. It felt magical honestly to go from the hustle and bustle of the day, step into the building, and then enter your own quiet oasis. The apartment is a studio, with decent closet space, a kitchen area, a couch, etc. It worked just fine for my wife and I for a week.
Communication with Christina was at times a tad slow (24+ hours between responses), but she responded quickly when it mattered. Public service announcement for Athens in general: do not flush the toilet paper! We did end up clogging the toilet, which was entirely our fault, and Christina sent a plumber over promptly.
Two last notes:
1. The apartment is located on the 3rd floor (4th in American parlance) right next to what is a travel agency, I believe. The key that opens the apartment door sort of looks like a car key - it took us a bit of time to figure out which one to use.
2. Grab-and-go food is less common in Athens than in the United States, but there is a Souvlaki place and a McDonalds just up the street toward Syntagma Square. There is also a market/bazaar down Ermou near the Metropolitan Cathedral.
Overall, I would definitely recommend!