https://appbot.co/blog/writing-a-great- ... escription
A potential customer has liked your icon enough to tap through, they've checked out your screenshots and are still interested, until they come to your drab App Store description when they hit the back button and go to download your competitor's app. Sad trombone.
I've managed to build a number of apps that have acheived millions of downloads on the App Store. So I've had a lot of practice tweaking App Store descriptions, here is what I have learned:
Social proof is really, really important
Sure this is a chicken and egg problem, but if you have any stats to brag about don't hold back! Have you had millions of downloads? Has Apple featured you? Have you had awesome press? Does your mum love you? Brag away!
Tell a story, don't rattle off features
Selling a story of the person your potential customers want to be is what you are trying to achieve. Are they going to be awesomely productive? Are they going to save money? Are they going to get fit in just 7 minutes? Tell me about the super human I will become using your app.
You only get a few lines, most people won't read the rest
The App Store will only show a few lines unless the user decides to click on the more link (which they most likely won't). So make sure you cram all the good stuff at the top.
Localize!
The majority of the world don't speak English, so you have to speak their language! Start with English and Chinese (Simplified and Traditional), Japanese, Spanish, French, German, Russian, Portuguese and Korean.
There are a bunch of services out there that will localize for you, ask a friend or try out a site like Fiverr.
Experiment
The only way you are going to know what works is by experimenting, try different wording and numbers. If your sales go backwards you can always revert.