When I used to work in downtown Brooklyn, I would occasionally stop by the original Junior's diner to get some cheesecakes and coffee. The diner, in my opinion, has lost much of its appeal due to poor customer service and mediocre food, but the cheesecake is still king. I have not been to the other two Junior's restaurants in Times Square or Grand Central Station but I hear the food and service are better there.
During holiday seasons, it is not uncommon to see a line of people at the diner and restaurants. especially at the take-out bakery section. It seems like everyone is there to buy a cheesecake (or two) for their families or friends.