To set the context, My wife and I went here with very expectations. We had just watched the chef's table episode and were very excited for the food, service, and overall dining experience.
The biggest issue we had was the service. The waiter who took our order was extremely brief with his explanations of the tasting menu items and the other waitresses who served the food did not take the time to explain the courses as they served them.
Additionally the waiter who took our order said "our tasting menu is very flexible and you can change how you like". I decided to change the main meat course of Pigeon to the ribeye, because I love ribeye. When I changed the course and asked the waiter if he thought the ribeye was great, his response was "whatever- I don't know why you're changing the menu".
The other line I heard him say to all tables was, "if you don't like the food, please let us know and we'll switch it out". A great and very respectable comment from a top restaurant. However, he followed that comment to us with, ".... But you won't not like the food, ok". After leaving us with that, he never returned to our table again.
Overall, the food and presentation was great as expected. However, it was mind-blowing above some of the other pintxos spots that we tried around the old town.
Therefore, for the rude,poor service couple with the good, but know mind-blowing food and massive price tag: I would say to stay away from Arzak or come with much lower than 3 Michelin star expectations.