We have eaten there once. It is an appealing space but quite small. There was outdoor seating but I imagine this isn't set up for winter. We had bocadillos. My wife had the chorizo and I had the tortilla. They tasted good but the baguettes were substantially heated to a very crusty finish which I didn't expect and my wife especially didn't want for a cured meat sandwich. I thought the tortilla was decent. They say that they use a toasted Columbia City ficelle baguette and arguably a ficelle, being thin, should be a good style for bocadillos but I don't recall the bread when we were there being particularly ficelle-like. When you look at pictures on the website and elsewhere you can see the diameter of the bread and how toasted it is. I eat Spanish food regularly and have traveled fairly extensively around the northern half of Spain in a number of trips over several years. It was an unusual preparation from my experience.
When we went (at lunch) the service was also very slow. The heating was part of it I think but they also only had one guy working in the kitchen when we were there. That also slowed them down considerably. We probably waited 15-20 minutes for our sandwiches, which was unbelievable as they only had one order as I recall before ours. Their kitchen guy also had trouble getting the orders right. Inexplicably he added cheese to the order before ours (which was in part the reason for the delay of our order) and also to my wife's sandwich.
As noted by Lavaca below it is also not necessarily a great value. Bocadillos are $7.5 to $9 ($6.5-$8 at lunch). That is not outrageous but the sandwiches were a bit meager when we visited. I did like the woman who was running the counter and again it is a very appealing spot in a reasonably quiet corner of Capitol Hill but we probably won't try again in the near future unless we start hearing reports of substantial improvements.
I had lunch there a few weeks ago. The food's decent but you don't get as much for your money as the menu may lead you to believe. It strikes me as one of those places that's a lot more enjoyable if you live within walking distance than if you don't.
(Admittedly, I've probably eaten a lot more Spanish food this year than the average Seattle diner so maybe my opinion is tainted by expectations.)