Efi's place is in a wonderful location. We didn't need to take the metro anywhere except for getting to the airport. There are lots of places to eat nearby, and despite being in the touristy area the food is actually reasonably priced and good.
The apartment has everything you need for an enjoyable stay.
The only things that bothered us a little was the noise from neighbours and also that the hot water didn't last long enough for 2 showers unless you waited long enough between.