My friend described this place as "a party for your eyes." My eyes definitely enjoyed this place. I'm usually not a fan of really tourist-y things, but this place was worth the visit. I'm also not used to paying $5 to enter a church but this is like no church I've been to. I'm sure that Europe has many churches that would be more impressive, but in North America, I don't know if you could find a more magnificent church.
I think if you're in Montreal, this place is definitely worth the visit. I didn't do the tour or use a map, but I was just fine wandering around.