As you know, with iOS 10.3, Apple finally made it very easy to request and post reviews while inside your app/game.
I have made a very small Unity native iOS plug-in, in order to use this functionality.
To use it, just call NativeReviewRequest.RequestReview(); and it is that simple. I guess the best place to use this is after a very memorable moment in your game, after a highscore, for example.
Download the plug-in from here:
Here are few screenshots what you should expect, when you call it:
And after you choose a star rating:
Submit is disabled, because I am testing this in a Development build.