It's a great walking nabe, so don't be afraid to come here early (before 11), beat the crowd, and eat well. Personally, I like to start at Avenue du Mont-Royal and walk down towards Sherbrooke,
The reason this is a 5-star (or 8-star or 11-star place) is because they do it right. There is never a bad bite in a Schartz's smoked meat sandwich, and that should be enough to garner four stars right there.
And, it is a sandwich - you can actually eat it with your hands. There's some more stars. This isn't the Carnegie Deli, selling you something eight inches high that you can't bite into, this is a real sandwich. Enjoy.
Plus, they treat you right, with a simple deli professionalism that gets you fed quickly and gives you time to enjoy. The sides are perfect deli style, nothing's been re-imagined and fusioned and brought into the 21st century, this is the real thing, traditional, and perfect.
Why bother if its "just" a perfect smoked meat sandwich? Well, if you like your brisket and you like your pastrami and you like your corned beef, you probably want this while you're in town, and there is none better. There are, I am told, places that are "about" as good - this one is definitely great. So beat the crowd, and go!