We spent two nights at Ramiro and Aitor's place. Ramiro was very kind and helpful and offered us all the information we needed for our short visit in Bilbao. He even provided coffee and cookies for breakfast, which was a thoughtful detail.
The apartment is very nice (it looked like it was recently redone). It is located in the 'Casco Viejo' area and is very close to pubs, terraces, shops, etc. The apartment was clean and the bed mattresses are comfy (which was a very pleasant surprise!). The parking spot is about 5 minutes away walking, and was very helpful, since it can be quite difficult to park around that area. The subway station is at about 7 min walk from the apartment.
All in all, we enjoyed our stay in Bilbao, thanks to Ramiro. I wholeheartedly recommend the apartment to anyone who wants to visit Bilbao and stay in a central area.