Rena's place is amazing. Though I never got to meet her, her Porter and staff were very friendly and I enjoyed talking with them. the house is in the heart of Oia, the nearest landmark on the main street I can think of is Atlantis Books, for reference, so it's pretty close to the tip of Oia.
The home is down quite a few stairs. I consider this a positive, as when you come to Oia you will see how many people wander up and down the cliffs for pictures, and all the people on balconies are within feet of the people on the street. Here, no one wanders by you as you are quite far down. If you have a tough time with stairs you'll have a tough time here (or anywhere in Oia for that matter).
The view is better than the pictures, and the house is adorable. Everything is just lovely. We even had a cake and wine in the fridge for us when we arrived, as well as coffee and anything else we would need, including toiletries.
The place really felt like a world away from the touristy chaos above. Tip for the sunset, unless you really really care about seeing it from the tip of the island, just walk down towards the parking lot 15 minutes before hand and see it set. you won't get the glint off the buildings, but you won't have to spend 3 hours sitting there with 1000 other people crammed in to see it. I didn't find it detracted from the experience.
Also the walk down to the water is worth it. It's a bit overgrown and has some slippery spots (so don't wear flip flops), and the beach is just big rocks, but it's worth it to swim. You are completely alone swimming in the Mediterranean, on the busiest island I've ever seen; it is worth it.
All in all, a great place and if we return to Oia we will stay here again!