We were very impressed with this property and had an amazing time staying here!
The house has two distinct apartments (the larger on the top floor/ slightly smaller on the bottom floor). There was a large living area in the top floor apartment that isn't pictured here and plenty of other areas if people need their own space. I can see how it might not be the best for 4 couples, with the single beds in the lower level, but for our group (2 families and 2 singles), the room configuration worked perfectly. Please note also that there was the air conditioning in every room and it worked great, which was a necessity in August and not always the case in Greece. There were several coffee makers: a filter coffee machine (which we used) and a nespresso (which we didn't use). There was ample cooking supplies and a grill, but we didn't end up using that either (too hot!).
Given the heat, we spent most of our time at the pool, which is indeed as big as pictured here and was great not just to lounge around, but really swim in. It is about 2 meters deep in the deep end to about 1.2 meters deep at the shallow end, so our 4-year-old couldn't stand, but she had plenty of room in the area around the steps to play in. We loved being able to dive and jump freely from the side and the diving board.
It is indeed someone's home and people should be respectful of that. There wasn't a lot of room to unpack, for example, but every bedroom had at least one drawer and hanging space for clothes. The owners were really great - communication worked perfectly and they even left us some wine and food for our first day since we arrived late on a Saturday.
A car is definitely recommended; the nearest major supermarket is about a 20 minutes' drive away. It's about a 15-20 minute walk or 5 minute drive to the main part of the town of Legrena (tavernas, bakeries, mini market, bus stop), but there are also 2 tavernas on the main shore road within a 5 minutes' walk of the house, both of which I would strongly recommend.
One member of our party who hadn't been to Athens before took the bus into the City for a day trip, so this is doable, but the bus trip takes almost 2 hours each way. By car it would be quicker, but parking is apparently very difficult. The temple of Poseidon at Sounio is an easy 10 minute drive and should not be missed, especially at sunset!
All in all, we loved our stay at this house and really hope to be able to visit again! Thanks for everything!