The Hard Rock Uyeno-Eki is located in the JR Eki (Japan Rail train station) building of Ueno. It is easily one of the smallest HRC properties I have ever seen, with very limited seating... I just ate at the bar so I could avoid the line for a table. Like all cafes in Japan, the service is impeccable, which cannot be easy given the cramped quarters that the staff has to operate in. The merch shop, while also quite small, seems huge when compared to the size of the actual restaurant. The atmosphere is a bit subdued, which is the norm for Japanese properties, but you can tell the staff is having a good time and working hard to keep the energy level up.
While not quite on the same level as the first Tokyo property in Roppongi, Uyeno-Eki is well worth a visit... especially given how easy the rail and subway lines make it to navigate through Tokyo. I suggest having dinner in Roppongi, then heading over to Uyeno-Eki for dessert (since they don't have veggie burgers there).