There's a reason why it's been in business for over 80 years! You have to eat here if you ever get a chance to visit Montreal. Been here 3 times at it's just as delicious as the first.
Get the smoked meat sandwich and ask for medium fat. You can get less fat or more fat, but in between is where the money's at. It's piled on top of rye bread and topped with mustard. I never liked mustard until I had it with some Schwartz's smoked meat! The poutine is just as delicious - the perfect side.
If you have a large group forget about getting a table without a long wait. 2 or less is ideal for dining in because you'll likely get a counter seat, but we still had a 20 minute wait at 1pm on a Saturday. We've been in and out in under 16 minutes, and in that amount of time you'll be sufficiently satisfied!