I have some - its not bad but its no miracle product. As far as a pre-wash - I haven't seen any real benefits there although it does remove some surface dirt if you soak the car in it.
However, I like to spray down the truck before I drive in rain - it does keep the splash and rain spots to a minimum. And if the truck is already dirty, a coating of Stage One before driving in rain and it's like a touchless car wash! I plan to try a diluted S&W mix or QEW for that purpose once I use up the Stage One. If one of those works as well, I will not buy more Stage One. But if they don't, I'll buy more.