Ganbara has two big cons. One, it's expensive. Raciones of mushrooms, for example, run you around 20 euros. Two, it's been discovered (twice over) and is on even the under-informed tourist's pintxo list.
That said, and considering that perhaps there is a causal relationship at play in this, the team at Ganbara brings traditional Basque cuisine to life, in miniature, and with an excellent quality of produce.
And who can resist the piles and piles of mushrooms and peppers that weigh down the bar?