To get to the top you take a cable-car type elevator which gives you a great view and is kind of fun.
There's really not much to say about the tower except that it gives you excellent views of the Olympic Park and all of Montreal, as well as the St. Lawrence River. If you're looking for scenic pictures, this is your place. Also there's the bragging rights of saying you've been in the world's tallest leaning tower.
It has a gift shop at the top as well, and interactive monitors that tell about some of the things you can see in and around Montreal.