Location: Far on Notre-Dame West. The closest subway is (I think) St. Henri.
The place: Totally unpretentious and super casual, just the way I like it. It was pretty dead when we went, but then, it was only 4:30. I guess the rest of Montreal starts boozing later than we do. The music is kickass awesome. AWESOME! Some old-school alternative, some Tom Waits, some urban electro. I. LOVE. IT. Music is a big factor in whether or not I will frequent a place - Bar de Courcelles was a total hit for me. They also show the game, for all you HABs fan. According to fellow Yelper Marko, this place really packs it in late in the evening, so if you're not feeling a crowded space, just go early and leave before 11pm.
Service: Can't really say because I only got a glass of water. The waiter/bartender was pretty cool and didn't have any issues with me not ordering anything. Bonus? Free nuts. Yum.
I say go for it. It's the kind of place you want to be in while a winter storm rages outside. Freezing cold out there, warm and cozy in here.