Joseba is a great guy. Very friendly, fun and interesting to talk to. We went out for a beer and snacks one evening with another guest.
The apartment is a bit old, so the floors squeak a bit when you walk. The room was adequate in size but the kitchen and bathroom were a bit cramped. Mosquitos are an issue in Bilbao when it rains. A couple of nights a got a mosquito in my room and was tough to get a good night sleep. Keep the windows closed.
Joseba offers basic breakfast food, like coffee, bread, butter and some fruit. The place is very centric to most major points of interest in the city.