It doesn't, App Store is all about impulse purchases. Anything remotely casual should be .99c or free, use ingame purchases to capture extra value. If the game plays half decent and is shiny(has non-amateur art), it should have a pop up sometime ingame reminding players to review and it will have no problem getting a 4-5 star rating. All of which doesn't actually matter if you get right because you still need a hook or angles that gets people playing YOUR game instead of the 1000s of other similairly polished and entertaining games(many of which are going to be better known, by virtue of branding/bigger marketing budget/connections/whatever)