I developed and maintain an app for education with HTML5 interactive books. The app runs on Android, Chrome OS, Mac, Windows, and iOS.
Of all the platforms, iOS is the only one causing problems with the webview and we are starting to seriously consider moving out of iOS in the next years since we can influence the device the schools/parents are buying.
For example we have one bug where the keyboard stops responding. Apparently this was solved in WKWebView, but we are forced to use the old UIWebView because of other bugs with WKWebView Apple hasn't solved.