I don't know about the J Hotel.
But I re visited J Korean Restaurant on the 1st floor of the Hotel.
It was good service. However they almost fully reserved insider Room tables they let us sit in outside designed area, which is covered by wall. In sunny days they let them open and people could sit outside.
Food was good. I think they have Korean Chef. The Korean owner man was hardworking. And staff girls were kind enough.
Restroom was very tiny in the Lobby area.
Glad they served us, even they had bookings.