Too many notifications and required user interaction while driving in heavy traffic
Of course I must have been crazy to try to navigate through Germany while knowing that it was one of the infamous black Saturdays.
One of the things annoying me the most however was not the fact that the trip took three extra hours, but that Tomtom kept asking me if it should take another route because it would take 2 minutes off the total travel time. I know you can switch that off, but I was driving!
Every few minutes Tomtom would notify me of an alternative route and ask me if I wanted to divert or not.
After a while I had enough of all that crap and switched to Apple Maps. Not known for its greatness, it did have one great plus: it displays the route you are on, and displays one or two alternatives, stating "3 min. shorter", or "10 min. longer". Just that, no need to hit a button on a small phone display.
No more bells and whistles, no required user interaction, just plain and simple. Also, the layout of maps, etc. was a lot quieter. Of course all was not perfect, no speed limit, no current speed, but all the other essentials are there.