Don't get me wrong, I love aquatic animals and wildlife so it was great to visit the Aquarium, but isn't something I would feel the need to do again.
I got the CityPass (highly recommend - you save serious $$$ if you want to do all the Toronto touristy stuff) with two others and luckily we got there early enough to avoid the massive lineup. My only complaint about the Aqaurium is it was suppppper crowded. So crowded at times it was hard to see all of the displays. Also there's one point where a moving plank brings you along through the exhibit. It moved so slow - too slow for me.
The displays are beautiful but I found them to be a little small for the number of aquatic wildlife in them. It made me a little sad to see. The layout of the Aquarium itself is beautiful with many different sections but I would like to see bigger areas for the fish. I didn't get to see any of the shows, which maybe would have made the experience better.
It's a great place for kids with a lot of fun interactive activities, but if you're a young adult (such as myself) I suggest going at a later time to avoid all the screaming children. Overall we stayed for a little over an hour.