Sears Tower to open glass bottom box at 1300 feet

In July, the Sears Tower Skydeck will open "the ledge", its newest attraction. 

The "ledge" is a glass box extending 4.3 feet out over the edge of the 103rd floor, offering an unobstructed view of the city. Up to 5 guests at a time will be able to stand on the inch and a half thick glass. 

I have a lot of faith in structural engineers, but I'm just not sure I'd feel entirely comfortable stepping out on this thing? Would you?