Yes, 英語國際音標全息速成 is free to download, however it contains in-app purchases or subscription offerings.
Not enough reviews to make a reliable assessment. The app needs more user feedback.
英語國際音標全息速成 has several in-app purchases/subscriptions, the average in-app price is $60.00.
To get estimated revenue of 英語國際音標全息速成 app and other AppStore insights you can sign up to AppTail Mobile Analytics Platform.