We absolutely loved Jj's place!! You cannot beat the location; it's in a neighborhood where you feel local, but it's still walking distance to all the main attractions. There is a very nice bar just downstairs, we ended up spending my Birthday evening there having pintxos and drinks.
The apartment itself has a very cool flair, and some nice details in the decorations. And it is very spacious, more so than you can see from the pictures.
Jj was an absolute gem for a host, he had so many good recommendations for restaurants, and things to do, and the check-in process was super effortless.
I would recommend staying here 100%, if you ever come to Bilbao!