I recently stayed with at Georgia's house with 5 friends (6 people in total).
We really enjoyed the experience! The house is located close to the port (10 minutes walk from the ferry). You pass by 3 of Ermoupoli's main attractions (the town hall, the theatre and the church of St Nicolas). The final couple of minutes are a bit of an uphill struggle but you get rewarded by an amazing view of the city from the terrace. Also Georgia came to the port to pick our stuff up and had a cold bottle of wine ready for us which helped a lot!
The house itself is very colourful and by far the most interesting house we spent time in using airbnb! Note that there are no airconditioners but if you strategically leave certain windows open there is a cooling breeze though the house.
All in all we all really enjoyed the house and we definitely recommend it, either for families or groups of friends.