App reviews and ratings provide customers with a valuable tool for providing feedback on their experience with your app, from the things they love about it to the features they would like to see added and the bugs they'd like to see fixed. Potential customers expect that the reviews and ratings they see in the App Store have been earned legitimately and have been given by real customers who have actually used your application.
Paying or soliciting others to falsely inflate or manipulate reviews for your app degrades the accuracy of your ratings and diminishes the overall effectiveness of the reviews and ratings system, which customers and developers depend on.
Generate positive feedback from your customers by building reliable apps. You may even want to consider designing your app to ask users to rate it on the App Store after being used a few times. Keep your ratings genuine and you'll go a long way in keeping your users' confidence and trust.