Rena was a great host and the cave house is very cute. Communication was great and she was very responsive. She helped arrange my transportation to and from the airport and also offered to arrange a porter to help me find the meeting location for one of my tours. I could not find my way back to the cave house my first evening there (note: the paths with stair steps in the cave house area are not on Google map), so after attempting for 15 minutes I texted Rena and she was able to rescue me within minutes. :)
The place itself is interesting - I love the decoration and the collection of the CDs she keeps there (classical and opera). I enjoyed making a good shot of espresso with their illy espresso machine every morning. The patio area is nice and bright during the day and I was accompanied by at least 2 adorable cats every time I spend time there (writing postcards, drinking my espresso, etc.). It's also a great place to lounge and watch the (abundance of) stars at night. The water pressure in the shower was a bit lower than expected but I heard that's common for a lot of places in Santorini due to the lack of water on the Island. The location of Rena's cave house is great - very close to all the shops and restaurants in Oia's centre.