This is one of those places that you must try in Montreal.
So sure, you will be queuing outside for a while and yes you will be seated at a cramped table with unknown people next to you but hey that's part of the experience! (lock your asocial self away for an hour, it will be worth it!)
Get the smoked meat sandwich and whatever else you fancy. Take picture and look in your neighbours' plates (don't drool, they don't like it!). Eat and watch the waiters run around as if every sandwich was important (but it is, right?!)
Then leave, full and smiling of what you just achieved! Be proud, you managed to eat at Schwartz's!