This was my first stop on my first full day in Montreal. After a rough evening the day before, I had dialed my expectations back - however, the friendly greeting by two church employees (volunteers?) and the absolute beauty of the chapel itself put me back on track.
I got the audio guide, and for only $5 I really recommend it. The guide will provide general background information on the chapel itself, its history, and many of the decorative touches that adorn the interior. Do you know why those hearts are hung on the wall near the altar? Why models of ships are hung throughout the nave? How the interior painting was thought to be lost? You will if you get that guide. It was also a welcome excuse to sit, out of the heat of the day, listen, and learn.
I'm guessing that most tourists begin and end their church visits at the Notre Dame Basilica up the road - don't be that tourist. Head the few blocks north and enjoy.