It would be a great place if they would not let so many people in at once. During my visit the aquarium was extremely crowded. We had to skip some attractions just because of the amount of people.
Also 80% of the people are doing photos CONSTANTLY. This is super annoying and ruins the experience.
We walked through the whole aquarium in about 30-40 minutes. Probably we would spend more time on it if there would be less people.
If you want to visit Ripley's Aquarium then do not go during holidays or weekends.
Overall, I would recommend visiting since in my opinion this place is one of the must see attractions in Toronto area. You can spend a good quality time there, but as I wrote before - avoid crowds.