Xabier is an excellent host - very responsive and helpful with suggestions or arrangements. The apartment is also very comfortable and in a very convenient location - a 15-20 minute walk to all major sites such as the Guggenheim Museum, old town and the funicular. There are local shops to buy food next door and within two blocks, and also two nice places for pinxtos also within blocks nearby - Colmado Iberico and Sukalde.
Legal AirBnBs need to be on the first floor, closer to the street. As one of us is a light sleeper, we noticed that the weekend nights had more street noise into the late evening. But for someone used to urban living, this probably might not be noticed. And given all the other positives about Xabier as a host and the quality and location of the apartment, we sill highly recommend it.