Google Now On Tap is one of those features that sounded great when it was announced, but has failed to live up to the hype now that it's out. It's not going to remain in that state forever, though. Google is already adding new features to On Tap, including some we've already noticed. A blog post on the Inside Search blog lays it all out.
If you're picking someone up from the airport, you can use On Tap to display flight information when they tell you the flight number. Looking at a shipping confirmation email? On Tap can pull up the tracking info without kicking you over to the browser. On Tap can also deliver relevant news links directly now as well. Previously you would just get a link to news stories, but now individual headlines are shown.
Google also mentioned the screenshot share button we noticed recently. It captures the screen and then opens a share intent immediately. Lastly, you can now get On Tap in more languages: French, German, Spanish, Italian, Russian, and Korean are all supported. It looks like the most recent builds of the Google app enable this stuff, so grab them from APK Mirror if you don't have them already.