Most important thing to know here is: TAKE YOUR OWN WINE.
They do not have any wine, or beer, or any sort of alcoholic beverage. So if you don't want to be washing down your amazing Quebecois/Greek cuisine with a diet sprite, buy a nice bottle and carry it with you. Also, the convenience store across the street has vinegar for wine and its dear.
Next, there will be a line outside. It took me nearly an hour to get in, in the Montreal winter. Well worth it for a good meal.
Right past that little hurdle, the food is amazing. Large hearty portions of whatever you order; I had the lamb and it was fantastic. The bread they serve it with is fresh and fluffy like a pastry, and the salad dressing - complimentary salad - was just the best dressing I've ever tried.
So truth is I went here after I got turned away from Au Pied Couchon (across the street), which some people will claim is the best restaurant in Montreal and hence obviously requires reservations six years in advance (and don't try to claim you're from their courteous neighbour in the south, it makes things worse). Fantastic decision in the end.