When my husband (then a boyfriend) and I were walking down rue st-paul est in vieux montreal, we spotted a group of Japanese people going into this restaurant. Then my hubby went, "Hey J people went in there, they always know where it's at." lol And he was right, they do know where it's at.
The best steak tartar! The best oysters! The wine selection... the flambee crepe, desert.... OMG everything we ate were ecstatic! Since then, everytime we visit Montreal, we make a point to go to this restaurant. I would say it's better than most of the restaurants I went to in Paris. Just go there.
Attire, business casual or above. Very old school French, classy place, so I would suggest you be dressy.
*note: I went there before 2008 so the review is based on that.