Yikes...in comparison with Andalucía, euskera almost sounds castellano!
Thanks for getting my point, Kelar...obviously in a cosmopolitan area like Bilbao, you'll be fine with castellano (as you no doubt have experienced).
Actually, for someone like myself, who already has a fluency in castellano, Bilbao is perfect, as you afford yourself the opportunity to go beyond and pick up euskera (or catalán, gallego, etc. depending on the area). [Plus, the food in Euskadi is so much better than in the meseta.]