Wow. I wish someone had stopped me from going here. It totally ruined my last day in Montreal.
The food... don't. buy. any. Bring your own. You will end up paying $11 for soggy/half cooked fries and only a handful of them. If this happens to you and you complain in English then you are invisible.
The lines are insane but that's to be expected. The issue was that the fast lane keeps going ahead at many rides without the staff letting us peasants from the normal line onto the ride - obviously this terrible system makes wait times extra long. We rode something like 8 rides all day. At Canada's Wonderland I ride them all and sometimes twice, no fast pass, my whole life. La Ronde has some serious organizational issues to tend to.