My two friends and I enjoyed our stay at Nelly's place. Her cousin Niko was our primary contact in Athens, and he responded to all our questions and concerns promptly--even when our flight landed past midnight! Niko also assisted with organizing our cab rides to and from the airport, for which we were very grateful.
The apartment is spacious enough for three people, and the kitchen is well-equipped. The third bed is actually a sofa bed, but it's a big one, and it was comfortable. We thought the neighborhood seemed kind of shady, but we felt safe traveling as a trio of females, and we made sure not to stay out too late. The two nearby metro stops are 5-10 minutes away by walking, and the Acropolis is about half an hour's walk.