I've done it before on a personal project and I was pretty obsessed with user experience. For example, I changed the way buttons work (because they were natively links with Cordova, which trigger upon tap, not "finger lift", like native buttons). Also, implemented some gestures to e.g. switch between pages (tab-style navigation). While not really in line with system UI (wasn't my goal), I think usability is quite decent.
In case you're interested, the app is named "QuickÖV" - not relevant to anyone outside Switzerland, but just for trying it out: https://play.google.com/store/apps/details?id=com.billhillap...