Panagis's flat was as described and we enjoyed staying in Spili and the flat.
Some reviews mentioned that the flat is noisy. The flat is in the village square of Spili and there are quite a few restaurants and cafes just below it and in the immediate area, and on Friday night there were people in them until late, but the "noise" was only people talking -- no music or drunken shouts, and it didn't bother us. If you are extremely sensitive to noise it might bother you, but not otherwise.
Communication with Panagis was excellent. There is a guide to the area in the flat and Panagis was happy to give us some more tips when we asked. Thanks to the guide we visited the Agios Antonios gorge which we enjoyed a lot. It's a good walk on a hot day since the gorge is mostly shady.
The only con we have for the flat is that the bathroom is quite tiny, but considering we spent most of our time outside the bathroom, it was OK.
Spili itself is a nice village which is nearby to some nice beaches (Triopetra and Ligres) and the mountains. The road to Agios Antonios gorge, which passes through the village of Patsos was breathtaking (literally, at some parts).