I'm a huge fan of the DC Jaleo (to which I have been going regularly for the past ten years). It's our home away from home and is keeping us going while we work out the logistics of moving to Spain for a year or so.
I recently ate back-to-back at the DC and Bethesda branches of Jaleo and felt compelled to report back...
I was quite surprised to find the execution of the dishes to be drastically different and inferior at the Bethesda branch.
None of the ten dishes that we ordered matched the quality of the downtown branch. And some, while not bad, were not correct renditions. For example, patatas con cabrales with no discernible cabrales present. Patatas bravas that were not brava (where was the smoked paprika?). The buñuelos de bacalao (cod fritters) that are so light and well-executed at the downtown branch were lumpy and not of the best flavor. There was an overabundance of alioli added to many dishes that didn't need it.
Basically, everything just tasted blander and lacked the simplicity and clarity of the flagship's kitchen.
And the ambiance was dead! There were only a handful of people there at 9:00 and we were informed that we had to order quickly, as the kitchen was closing soon--no real time for dessert or coffee. In fact, that whole street was like a ghost town, even at 7:30.
Given the dearth of quality nearby options, it's still probably a fine place to go if you are in the neighborhood. I might go again if I catch a movie at the theater on the same block (but with Landmark opening a downtown branch this month, that's doubtful).
But if you are going to travel any kind of distance or you have an interest in Spanish tapas, I would strongly recommend going to the downtown branch. The best time to go is for a late weekday lunch, weekend lunch, or an early dinner before 7:30. Otherwise, you are in for a wait, particularly on the weekends.