Nice little studio, close to various bus lines. The metro is somewhat further away and you have to do some uphill stair climbing or walk uphill - we did that as sport on the first evening ;) Later on we discovered the bus back "home".
If you come by car, there's free parking nearby where you can leave the car also overnight.
Germán is a great host who even picked us up at the airport when I told him that we'd arrive late and how to traverse Bilbao :O He gave us a lot of tips and things to see in Bilbao and around.
The studio itself is totally clean and nice, and has everything one might need for a few days in Bilbao, including Nespresso coffee tabs, breakfast supplies and a splendid view over Bilbao's hills.
It's a nice residential neighbourhood, very green and calm, even when you come back home late.