It's a tourist thing to do.. Just going once is more than enough!
Comparing to Tokyo tower, Shanghai Pearl Tower, and others, I actually found this a little lacking in terms of information.
I went up all the way to the top, but it didn't have any information about the tower or Toronto. It doesn't have information what you are looking out at. Before the elevator, it said it can see as far out as Niagara Falls but no one know which windows we need to look out at. With the long wait on the elevators, but at most you can spend on top is maybe 5-10min...
The 4-6 glass panel Sky floor is cool.
For better deal, just buy a drink at the 360 restaurant and you can see the same view as the glass sky floor level