I much enjoyed my stay at Jon and Manex's place. Everything was very clean (as one would expect in San Sebastián). The place is beautiful, and very tastefully decorated. Jon (the one who greeted me) was friendly, helpful, and responsive to my messages. The kitchen is huge, full of light, and there were all kinds of things available for breakfast - and even beyond.
What I had not realized (and this is probably my mistake) is that there are multiple rooms (three, I think) at this location. I was fortunate that for most of my 5 night stay, I was the only guest. The one night that there was someone else, I was able to hear them (things like footsteps in the hallway, water running in bathroom etc). This was not a problem for me, but it did make me aware that if other guests were talking loudly or playing music, that could be irritating if one was trying to sleep. The street itself is a quiet one, unlike some of the streets in the "parte vieja".
All in all, an excellent stay!