If you have the opportunity...do this!
My girlfriend and I did the edge walk on a recent trip to Toronto and the experience was well worth the price. After taxes it ended up being about $200 /person.
There's a separate area in the lobby of the tower where you meet in groups of 6, reservations are a must. They give you some basic safety and instructions for the walk while giving you your jump suit and shoes. They also breathalyze everyone before the walk... luckily I only had 3 beers at the Blue Jays game beforehand.
They do not allow you to wear any jewelry or carry anything at all in your pockets. Jewelery can be taped if it can't be removed.
After taking a private elevator to the top we have our harnesses checked, for the 3rd time, by another member of the staff. You are then hooked to a trolley which you will be attached to for the entire 30 minute walk.
Once outside the guide encourages you to lean forwards and backwards off the edge of the platform but they do not make anyone do something they're not comfortable doing.We went on a gorgeous, clear day and could see all the way to Niagara and Rochester. The first few steps out can be quite an adrenaline rush, especially as you approach the edge for the first time. The guide will also point out different landmarks and sites around the city as you stop at all 4 sides of the tower
The guide was very friendly and informative, as were all the staff that I encountered at the Edge Walk.
After the walk they gave us our video and pictures, which are part of the package, along with a USB stick, $15 extra, with all the picture files.
So if you're thinking about trying this, just go for it, and don't chicken out! You won't regret it. It's one of the coolest things I've done in a long time and I'll never forget it.