Google says that the AR feature is not to be used while driving. The Googler who is the lead on the project, Rachel Inman, says that the Google Maps AR navigation is “for those moments like, ‘I’m getting off the subway, where do I go first?'” And if you put the phone down for a second, the AR mode turns off to reveal the standard Google Maps UI. To prevent users from paying too much attention to the screen in front of them and having an accident, Google Maps reminds them to put the phone down. If the user fails to heed that advice, the screen automatically darkens. It also does this to prevent the battery from draining on a user’s phone.
It might be some time before Google says that AR navigation is ready for prime time. But once it is, those requiring Google Maps for walking directions will be entering a new world where they can be given information about the places they are walking by. Those traveling by foot in a foreign country can use the AR navigation feature along with Google Translate to read signs in their primary language.