It can be helpful to get rerouted on a different route ahead of time if traffic is busy.
It shows speed more accurately (if travelling at a steady speed).
Warn of speed cameras etc.
It used to display a convenient “skip forward” and “pause” button for my podcasts. But for some fucking reasons Google decided to take that feature away by removing Android Auto. And alternative navigation apps don’t have it.
It used to tell me my average speed over the journey. Which was just a pretty fun bit of data to see. (The vast majority of my drives, excluding ones after 11pm at night or which were majority on motorways, averaged less than 40 km/h.) But again, for some fucking reason, Google removed this feature, and alternative apps I’ve moved to don’t do this either.
I use my phone for navigation for a few reasons.