I came here with friends while the Christmas Market was going on. Although the atmosphere was great, the waiting times for ordering anything took forever. El Catrin has heaters outside during the winter, but the patio was still cold and there were no blankets available at all.
We ordered mulled wine and this really took a long time to get that we decided not to order food in the end, although we would have liked to if the service were better. The wine was served in a plastic cup which should not have taken so long. Definitely try the mulled wine if the line is not long!
The inside was only available to people with "reservations." Consider making a reservation during the Christmas Market season to avoid sitting outside in the cold.