I came here to check it out after the New York Times ran an article about Montreal and mentioned this place. Give yourself a whole afternoon if you want to come here and check out the myriad of stalls and sellers while you go bargain hunting, vintage hunting or even just browsing.
If you're the kind of person who gets overwhelmed easily and don't know what you're looking for or what you're looking at, don't bother. If on the other hand, you enjoy digging, rummaging and pretending you're on a treasure hunt, if you can spot quality vintage stuff from several feet away, you can name several types of quality vintage brands which have long since disappeared right off the top of your head (i.e FireKing, Jadeite, Descoware, Catherine Holm, Dansk Kobenstyle, Luminarc etc.) then this place is the mother lode for you.
Haggling over prices is encouraged.