I live right next to this spot and every morning I wake up to the smell of roasting beans. Pretty delightful. Some say it's smells a bit like burnt toast, i'd say it smells like awesomeness mixed with peppers.
They are in fact one of the oldest operating coffee roasters in Montreal, with more than 100 years in the making of the perfect bean. They have a pretty wide variety of essences and you can, as always, do your own mixes. If you are a restaurateur, they have everything you need, from machines to delivery.
Price is good, and they sell all that fancy stuff, like the Trudeau collection and some really neat European collections related to the 'art' of making coffee. They also have a service and a repair section.
So next time your are wondering about where to find good coffee beans in Montreal, and an all lot more, Cafe Union is the place to go. Parking is easy too. If you are ending up buying one of those fancy espresso machine :)