We (four adults), spent a week in Romanos' place, and thoroughly enjoyed it. The location of the flat was great, and we could walk to most of sightseeing places in Athens. The tram stop (5) that takes one to the beach (our favourite, even in March was called 'Zephyros') in ~30-40 min is 5 min walk from the apartment, and so is the metro stop which takes one anywhere you like! There are two supermarkets about 2 min walk each, as well as an incredible bakery next door (open early to late), best sandwich joint in town on the other side, as well as fresh fish/seafood shop across the road (buy in the morning!). Two door from fishmongers is the wine/spirits place, which sold a massive selection of local wines on tap (from barrels) for under 4eur/l. If you are into running, ~2 km running roughly uphill will take you to the Philopappos monument with stunning views of Acropolis and rest of Athens, or running other direction you might find yourself running on top of the Panathenian/Kallimarmaro stadium (i thoroughly recommend this!).
Flat is quirky is the best way possible, with lots of interesting furniture, and a well-stocked kitchen (which we used a lot to cook). A/C in every room, comfortable enough bed/sofa-bed; elevator in the building. We stayed in March, when heat was not an issue, but it feels as if it would be nicely cool in summer.
We've had great welcome by Petros from Romanos' team, including a good list of tips on things to do, places to eat in, etc.
Very positive experience all-in-all, and we'd love to come back!