It's a great apartment in a really central location - I would recommend it to a couple or friends who wanted to get around Bilbao and enjoy all the sights.
Xabier was there to meet us, so it was a hassle free experience too.
If you need to stay somewhere that is squeaky clean, and you want your host to make a fuss of you and tell you all the best places to stay, I wouldn't pick the apartment but if you are fine with low-key, then this is great.
Make sure if you are using the extra bed Xabier gives you enough bedding the first night!