On a normal day I would describe this park as: A rather small amusement park located on an island in the city of Montreal, where the pricing is average, the rides are average, the food is average, hell the whole park is pretty much average.
On Halloween however the park comes to life, with special haunted houses and people walking around in costume.
The one negative thing about that is however, that you have to pay extra for the haunted houses..even when you have a season pass.
Conclusion: It's alright, not a magical adventure, but it's something to do when you're bored and have the extra cash.
Personally, I'd stick to only going on/around Halloween, it's way more fun.