We had a lovely stay at Maria's apartment! The space was extremely clean with helpful touches such as coffee and basic groceries. The terrace is phenomenal: spacious with a gorgeous view. The host who let us in to the apartment (Sophia) was very sweet and helpful, giving recommendations for bars and restaurants in the area. The location is also superb, easy walking distance to all major tourist sights, with tons of bars, restaurants and shops in the area.
The only minor issue was the wi-fi is very weak (the router is not located in the apartment). It was functional, but requires some patience and not strong enough for streaming or phone calls or anything of that nature, so if you're dependent on the internet for work or anything else, it could be an issue. However, if you just need it for checking e-mail or whatnot, it should be totally fine.
Overall a wonderful place to stay in Athens.