Ask HN: Not getting good feedback on US App Store?

3 months back, I made an app to learn iOS development and happy with the results submitted it in the app store as paid app. Since then, I improved it a lot and the final version (which I think is good enough) is under review.

The problem is, I am getting lot of negative feedback on US App Store. Don't know what the problem is, but except US in all other countries (Germany, UK, Japan, Australia) I am getting quite good reviews. They are encouraging and push me to make more improvements in app.

What to do now, as the average rating in US app store has dropped a lot now.