The location is hidden deep in the residential area. Generally speaking, diners are nearby residents. There are only four different tapas on the pub’s menu. The prices are very cheap and the portions are full. The general owner would suggest ordering one for each one, and then adding more dishes according to your preference.
Just five menu items (you must visit to discover them), cold beer, barrelled red/white/rose .... Perfecto and a must visit in Barcelona.
We went at a peak time, and the smallness of the place and number of people in there made it a bit intimidating, but as soon as we got the attention of the waiter/server and managed to get a seat, everything was fine. As others have mentioned, the menu is small, but everything on it is delicious; the fried fish was our favourite, to the extent that we had to order another helping! The dishes come quickly and are served as they're ready, so we found that we were gobbling them down quite speedily - but not with such greed that we weren't appreciating them fully. Wine (red, white, rose) is served from barrels in tiny, thimblelike glasses, and complements the dishes perfectly, both in size and in flavour. Service is quite brisk, but the man serving us was lovely; despite being probably the busiest person I've ever seen in a restaurant, and despite our lack of Spanish, he made sure we had everything we needed, and was pleasant and friendly throughout. We left feeling full and happy, and like we'd had an authentic Barcelonian (?!) experience - and all for under €25.