My partner and I ate here last week and it was an amazing dinner. The server was great and so helpful with the menu and wine pairings. The butternut squash soup and smoked shoulder/foie gras/bacon entree were incredible. We have a similar charming restaurant here in DC that's small and cute with superb food (Obelisk) unfortunately it's double the cost of Mas. We took a cab from downtown but after having used the Metro system, I'd recommend using it and hoofing it from the station--you'll save quite a bit of money. If you are planning a visit to Montreal, you'll definitely want to check out Mas Cuisine and La Salle a Manger (located in the Plateau). You won't be disappointed.
PS--my only complaint is the garish lighting in the kitchen that flooded the otherwise serene dining room.