We were a bit unlucky with our trip to Bilbao. It was raining most of the time that we were there and it was very cold (4-5 °C). The flat did not have central heating so we were freezing all the time. The friend of the host (spanish speaking ONLY) who welcomed us had a gas heater ready but to be honest as you had to light it with matches and it did not look like the newest model we did not dare to operate it ourselves. Also, we used all the three bedrooms so we could´ve never heated all of them anyways. The bathroom and especially the shower were not too clean and the water pressure on the shower was pretty poor so no chance to warm up with a steaming shower sadly.
The flat is really cute in terms of interior and all the art that is hung up on the walls. Also it has a balcony and is situated in a lovely and very lively old town quarter of Bilbao. I think if we would´ve visited in the summertime when the weather was better and much warmer we would have loved it here! So maybe it´s just not the right place for the wintertime.
Also, the WIFI did not work for the whole time of our stay.