This area of Athens is very lively with lots of alleys to explore. Niko took the time to give us some good tips around his area when we arrived, and showed us how to get to the roof (what a view!)
Niko's apartment is on the top of an older style building (with an elevator) that catches the breeze beautiully, and the screens on all windows and doors take care of mosquitos. Inside is very spacious and the outside patio is shaded in the afternoon. The kitchen has the basic implements if you need to cook. We stayed in a heatwave, and the apartment took a while to cool down when we came back of an evening, but sitting under the fan or air-con will make it bearable quickly.
It was difficult to find the entry initially as there was a heroic amount of graffiti on the entry (spotting the lock was difficult the first time), and the only reason that I can't give the location 5 stars is that I feel it would be very intimidating to walk down the alley as a single traveller for the first time (it was also unplesant early on a Sunday morning before it was cleaned from the Saturday night) but from the apartment you don't see or hear much of this at all. Please note that I didn't have a bad experience in the street at all - just ordinary, everyday caution made me wary, and my husband said that at home he probably wouldn't walk down it alone at night himself (but no problems here)
The area is vibrant, youthful and thriving - there are local antique and flea markets, amazing bars, many restaraunts and hoards of people out at all hours of the day and night. I understand that there nightclub district is close too (if that's your thing), and there are markets for your trinkets and souvenirs, interspersed with historical sites.
Finally, if you are depressed to leave Athens and fly out from the really remote terminal at the airport, you can see the building on one of the panorama photos between travelators. Overall I would stay there again in a flash!