It completely alters the angle of the ankles due to the heel. This in turn allows you to stay far more upright during the lift, which is essential for a decent front squat.
Not only that, you will also be far more stable during the lift. Personally, I would HATE to squat in anything other than lifting shoes these days. It is possible to replicate the effect to a degree with normal dress shoes if you want to test it out before forking out on the oly shoes.